diff --git a/go/packages/packagestest/expect.go b/go/packages/packagestest/expect.go
index 3a5d88e..cf4b673 100644
--- a/go/packages/packagestest/expect.go
+++ b/go/packages/packagestest/expect.go
@@ -106,11 +106,11 @@
 		for i, convert := range mi.converters {
 			params[i], args, err = convert(n, args)
 			if err != nil {
-				return fmt.Errorf("%v: %v", e.fset.Position(n.Pos), err)
+				return fmt.Errorf("%v: %v", e.ExpectFileSet.Position(n.Pos), err)
 			}
 		}
 		if len(args) > 0 {
-			return fmt.Errorf("%v: unwanted args got %+v extra", e.fset.Position(n.Pos), args)
+			return fmt.Errorf("%v: unwanted args got %+v extra", e.ExpectFileSet.Position(n.Pos), args)
 		}
 		//TODO: catch the error returned from the method
 		mi.f.Call(params)
@@ -154,7 +154,7 @@
 			if err != nil {
 				return err
 			}
-			l, err := expect.Parse(e.fset, filename, content)
+			l, err := expect.Parse(e.ExpectFileSet, filename, content)
 			if err != nil {
 				return fmt.Errorf("Failed to extract expectations: %v", err)
 			}
@@ -214,7 +214,7 @@
 		}, nil
 	case pt == fsetType:
 		return func(n *expect.Note, args []interface{}) (reflect.Value, []interface{}, error) {
-			return reflect.ValueOf(e.fset), args, nil
+			return reflect.ValueOf(e.ExpectFileSet), args, nil
 		}, nil
 	case pt == exportedType:
 		return func(n *expect.Note, args []interface{}) (reflect.Value, []interface{}, error) {
@@ -234,7 +234,7 @@
 			if err != nil {
 				return reflect.Value{}, nil, err
 			}
-			return reflect.ValueOf(e.fset.Position(r.Start)), remains, nil
+			return reflect.ValueOf(e.ExpectFileSet.Position(r.Start)), remains, nil
 		}, nil
 	case pt == rangeType:
 		return func(n *expect.Note, args []interface{}) (reflect.Value, []interface{}, error) {
@@ -369,9 +369,9 @@
 		switch arg {
 		case eofIdentifier:
 			// end of file identifier, look up the current file
-			f := e.fset.File(n.Pos)
+			f := e.ExpectFileSet.File(n.Pos)
 			eof := f.Pos(f.Size())
-			return span.Range{FileSet: e.fset, Start: eof, End: token.NoPos}, args, nil
+			return span.Range{FileSet: e.ExpectFileSet, Start: eof, End: token.NoPos}, args, nil
 		default:
 			// look up an marker by name
 			mark, ok := e.markers[string(arg)]
@@ -381,23 +381,23 @@
 			return mark, args, nil
 		}
 	case string:
-		start, end, err := expect.MatchBefore(e.fset, e.FileContents, n.Pos, arg)
+		start, end, err := expect.MatchBefore(e.ExpectFileSet, e.FileContents, n.Pos, arg)
 		if err != nil {
 			return span.Range{}, nil, err
 		}
 		if start == token.NoPos {
-			return span.Range{}, nil, fmt.Errorf("%v: pattern %s did not match", e.fset.Position(n.Pos), arg)
+			return span.Range{}, nil, fmt.Errorf("%v: pattern %s did not match", e.ExpectFileSet.Position(n.Pos), arg)
 		}
-		return span.Range{FileSet: e.fset, Start: start, End: end}, args, nil
+		return span.Range{FileSet: e.ExpectFileSet, Start: start, End: end}, args, nil
 	case *regexp.Regexp:
-		start, end, err := expect.MatchBefore(e.fset, e.FileContents, n.Pos, arg)
+		start, end, err := expect.MatchBefore(e.ExpectFileSet, e.FileContents, n.Pos, arg)
 		if err != nil {
 			return span.Range{}, nil, err
 		}
 		if start == token.NoPos {
-			return span.Range{}, nil, fmt.Errorf("%v: pattern %s did not match", e.fset.Position(n.Pos), arg)
+			return span.Range{}, nil, fmt.Errorf("%v: pattern %s did not match", e.ExpectFileSet.Position(n.Pos), arg)
 		}
-		return span.Range{FileSet: e.fset, Start: start, End: end}, args, nil
+		return span.Range{FileSet: e.ExpectFileSet, Start: start, End: end}, args, nil
 	default:
 		return span.Range{}, nil, fmt.Errorf("cannot convert %v to pos", arg)
 	}
diff --git a/go/packages/packagestest/export.go b/go/packages/packagestest/export.go
index e927313..cb9e6be 100644
--- a/go/packages/packagestest/export.go
+++ b/go/packages/packagestest/export.go
@@ -62,10 +62,11 @@
 	// Modules is the module description that was used to produce this exported data set.
 	Modules []Module
 
+	ExpectFileSet *token.FileSet // The file set used when parsing expectations
+
 	temp    string                       // the temporary directory that was exported to
 	primary string                       // the first non GOROOT module that was exported
 	written map[string]map[string]string // the full set of exported files
-	fset    *token.FileSet               // The file set used when parsing expectations
 	notes   []*expect.Note               // The list of expectations extracted from go source files
 	markers map[string]span.Range        // The set of markers extracted from go source files
 }
@@ -140,11 +141,11 @@
 			Tests:   true,
 			Mode:    packages.LoadImports,
 		},
-		Modules: modules,
-		temp:    temp,
-		primary: modules[0].Name,
-		written: map[string]map[string]string{},
-		fset:    token.NewFileSet(),
+		Modules:       modules,
+		temp:          temp,
+		primary:       modules[0].Name,
+		written:       map[string]map[string]string{},
+		ExpectFileSet: token.NewFileSet(),
 	}
 	defer func() {
 		if t.Failed() || t.Skipped() {
diff --git a/internal/lsp/cmd/check_test.go b/internal/lsp/cmd/check_test.go
index 0665b4b..4efd7d1 100644
--- a/internal/lsp/cmd/check_test.go
+++ b/internal/lsp/cmd/check_test.go
@@ -7,49 +7,38 @@
 import (
 	"context"
 	"fmt"
+	"runtime"
 	"strings"
 	"testing"
 
-	"golang.org/x/tools/go/packages/packagestest"
-	"golang.org/x/tools/internal/lsp/cmd"
-	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/tests"
 	"golang.org/x/tools/internal/span"
 	"golang.org/x/tools/internal/tool"
 )
 
-type diagnostics map[string][]source.Diagnostic
-
-func (l diagnostics) collect(spn span.Span, msgSource, msg string) {
-	fname, err := spn.URI().Filename()
-	if err != nil {
-		return
+func (r *runner) Diagnostics(t *testing.T, data tests.Diagnostics) {
+	if runtime.GOOS != "linux" || isRace {
+		t.Skip("currently uses too much memory, see issue #31611")
 	}
-	//TODO: diagnostics with range
-	spn = span.New(spn.URI(), spn.Start(), span.Point{})
-	l[fname] = append(l[fname], source.Diagnostic{
-		Span:     spn,
-		Message:  msg,
-		Source:   msgSource,
-		Severity: source.SeverityError,
-	})
-}
-
-func (l diagnostics) test(t *testing.T, e *packagestest.Exported) {
-	count := 0
-	for fname, want := range l {
+	for uri, want := range data {
 		if len(want) == 1 && want[0].Message == "" {
 			continue
 		}
+		fname, err := uri.Filename()
+		if err != nil {
+			t.Fatal(err)
+		}
 		args := []string{"-remote=internal"}
 		args = append(args, "check", fname)
-		app := &cmd.Application{}
-		app.Config = *e.Config
 		out := captureStdOut(t, func() {
-			tool.Main(context.Background(), app, args)
+			tool.Main(context.Background(), r.app, args)
 		})
 		// parse got into a collection of reports
 		got := map[string]struct{}{}
 		for _, l := range strings.Split(out, "\n") {
+			if len(l) == 0 {
+				continue
+			}
 			// parse and reprint to normalize the span
 			bits := strings.SplitN(l, ": ", 2)
 			if len(bits) == 2 {
@@ -60,7 +49,8 @@
 			got[l] = struct{}{}
 		}
 		for _, diag := range want {
-			expect := fmt.Sprintf("%v: %v", diag.Span, diag.Message)
+			spn := span.New(diag.Span.URI(), diag.Span.Start(), diag.Span.Start())
+			expect := fmt.Sprintf("%v: %v", spn, diag.Message)
 			_, found := got[expect]
 			if !found {
 				t.Errorf("missing diagnostic %q", expect)
@@ -71,9 +61,5 @@
 		for extra, _ := range got {
 			t.Errorf("extra diagnostic %q", extra)
 		}
-		count += len(want)
-	}
-	if count != expectedDiagnosticsCount {
-		t.Errorf("got %v diagnostics expected %v", count, expectedDiagnosticsCount)
 	}
 }
diff --git a/internal/lsp/cmd/cmd_race_test.go b/internal/lsp/cmd/cmd_race_test.go
new file mode 100644
index 0000000..dca3df4
--- /dev/null
+++ b/internal/lsp/cmd/cmd_race_test.go
@@ -0,0 +1,11 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build race
+
+package cmd_test
+
+func init() {
+	isRace = true
+}
diff --git a/internal/lsp/cmd/cmd_test.go b/internal/lsp/cmd/cmd_test.go
index 4151af5..5389664 100644
--- a/internal/lsp/cmd/cmd_test.go
+++ b/internal/lsp/cmd/cmd_test.go
@@ -7,166 +7,55 @@
 import (
 	"io/ioutil"
 	"os"
-	"path/filepath"
 	"strings"
 	"testing"
 
 	"golang.org/x/tools/go/packages/packagestest"
-	"golang.org/x/tools/internal/lsp/source"
-	"golang.org/x/tools/internal/span"
+	"golang.org/x/tools/internal/lsp/cmd"
+	"golang.org/x/tools/internal/lsp/tests"
 )
 
-// We hardcode the expected number of test cases to ensure that all tests
-// are being executed. If a test is added, this number must be changed.
-const (
-	expectedCompletionsCount = 65
-	expectedDiagnosticsCount = 16
-	expectedFormatCount      = 4
-)
+var isRace = false
+
+type runner struct {
+	data *tests.Data
+	app  *cmd.Application
+}
 
 func TestCommandLine(t *testing.T) {
 	packagestest.TestAll(t, testCommandLine)
 }
 
 func testCommandLine(t *testing.T, exporter packagestest.Exporter) {
-	const dir = "../testdata"
+	data := tests.Load(t, exporter, "../testdata")
+	defer data.Exported.Cleanup()
 
-	files := packagestest.MustCopyFileTree(dir)
-	overlays := map[string][]byte{}
-	for fragment, operation := range files {
-		if trimmed := strings.TrimSuffix(fragment, ".in"); trimmed != fragment {
-			delete(files, fragment)
-			files[trimmed] = operation
-		}
-		const overlay = ".overlay"
-		if index := strings.Index(fragment, overlay); index >= 0 {
-			delete(files, fragment)
-			partial := fragment[:index] + fragment[index+len(overlay):]
-			contents, err := ioutil.ReadFile(filepath.Join(dir, fragment))
-			if err != nil {
-				t.Fatal(err)
-			}
-			overlays[partial] = contents
-		}
-	}
-	modules := []packagestest.Module{
-		{
-			Name:    "golang.org/x/tools/internal/lsp",
-			Files:   files,
-			Overlay: overlays,
+	r := &runner{
+		data: data,
+		app: &cmd.Application{
+			Config: *data.Exported.Config,
 		},
 	}
-	exported := packagestest.Export(t, exporter, modules)
-	defer exported.Cleanup()
-
-	// Do a first pass to collect special markers for completion.
-	if err := exported.Expect(map[string]interface{}{
-		"item": func(name string, r packagestest.Range, _, _ string) {
-			exported.Mark(name, r)
-		},
-	}); err != nil {
-		t.Fatal(err)
-	}
-
-	expectedDiagnostics := make(diagnostics)
-	completionItems := make(completionItems)
-	expectedCompletions := make(completions)
-	expectedFormat := make(formats)
-	expectedDefinitions := make(definitions)
-	expectedTypeDefinitions := make(definitions)
-
-	// Collect any data that needs to be used by subsequent tests.
-	if err := exported.Expect(map[string]interface{}{
-		"diag":       expectedDiagnostics.collect,
-		"item":       completionItems.collect,
-		"complete":   expectedCompletions.collect,
-		"format":     expectedFormat.collect,
-		"godef":      expectedDefinitions.godef,
-		"definition": expectedDefinitions.definition,
-		"typdef":     expectedTypeDefinitions.typdef,
-	}); err != nil {
-		t.Fatal(err)
-	}
-
-	t.Run("Completion", func(t *testing.T) {
-		t.Helper()
-		expectedCompletions.test(t, exported, completionItems)
-	})
-
-	t.Run("Diagnostics", func(t *testing.T) {
-		t.Helper()
-		expectedDiagnostics.test(t, exported)
-	})
-
-	t.Run("Format", func(t *testing.T) {
-		t.Helper()
-		expectedFormat.test(t, exported)
-	})
-
-	t.Run("Definitions", func(t *testing.T) {
-		t.Helper()
-		expectedDefinitions.testDefinitions(t, exported)
-	})
-
-	t.Run("TypeDefinitions", func(t *testing.T) {
-		t.Helper()
-		expectedTypeDefinitions.testTypeDefinitions(t, exported)
-	})
+	tests.Run(t, r, data)
 }
 
-type completionItems map[span.Range]*source.CompletionItem
-type completions map[span.Span][]span.Span
-type formats map[span.URI]span.Span
-
-func (l completionItems) collect(spn span.Range, label, detail, kind string) {
-	var k source.CompletionItemKind
-	switch kind {
-	case "struct":
-		k = source.StructCompletionItem
-	case "func":
-		k = source.FunctionCompletionItem
-	case "var":
-		k = source.VariableCompletionItem
-	case "type":
-		k = source.TypeCompletionItem
-	case "field":
-		k = source.FieldCompletionItem
-	case "interface":
-		k = source.InterfaceCompletionItem
-	case "const":
-		k = source.ConstantCompletionItem
-	case "method":
-		k = source.MethodCompletionItem
-	case "package":
-		k = source.PackageCompletionItem
-	}
-	l[spn] = &source.CompletionItem{
-		Label:  label,
-		Detail: detail,
-		Kind:   k,
-	}
-}
-
-func (l completions) collect(src span.Span, expected []span.Span) {
-	l[src] = expected
-}
-
-func (l completions) test(t *testing.T, e *packagestest.Exported, items completionItems) {
-	if len(l) != expectedCompletionsCount {
-		t.Errorf("got %v completions expected %v", len(l), expectedCompletionsCount)
-	}
+func (r *runner) Completion(t *testing.T, data tests.Completions, items tests.CompletionItems) {
 	//TODO: add command line completions tests when it works
 }
 
-func (l formats) collect(src span.Span) {
-	l[src.URI()] = src
+func (r *runner) Format(t *testing.T, data tests.Formats) {
+	//TODO: add command line formatting tests when it works
 }
 
-func (l formats) test(t *testing.T, e *packagestest.Exported) {
-	if len(l) != expectedFormatCount {
-		t.Errorf("got %v formats expected %v", len(l), expectedFormatCount)
-	}
-	//TODO: add command line formatting tests when it works
+func (r *runner) Highlight(t *testing.T, data tests.Highlights) {
+	//TODO: add command line highlight tests when it works
+}
+func (r *runner) Symbol(t *testing.T, data tests.Symbols) {
+	//TODO: add command line symbol tests when it works
+}
+
+func (r *runner) Signature(t *testing.T, data tests.Signatures) {
+	//TODO: add command line signature tests when it works
 }
 
 func captureStdOut(t testing.TB, f func()) string {
diff --git a/internal/lsp/cmd/definition_test.go b/internal/lsp/cmd/definition_test.go
index d1388a9..0419b16 100644
--- a/internal/lsp/cmd/definition_test.go
+++ b/internal/lsp/cmd/definition_test.go
@@ -17,8 +17,8 @@
 	"strings"
 	"testing"
 
-	"golang.org/x/tools/go/packages/packagestest"
 	"golang.org/x/tools/internal/lsp/cmd"
+	"golang.org/x/tools/internal/lsp/tests"
 	"golang.org/x/tools/internal/span"
 	"golang.org/x/tools/internal/tool"
 )
@@ -28,21 +28,15 @@
 	expectedTypeDefinitionsCount = 2
 )
 
-type definition struct {
-	src     span.Span
-	flags   string
-	def     span.Span
-	pattern pattern
-}
-
-type definitions map[span.Span]definition
-
 var verifyGuru = flag.Bool("verify-guru", false, "Check that the guru compatability matches")
 
 func TestDefinitionHelpExample(t *testing.T) {
 	if runtime.GOOS == "android" {
 		t.Skip("not all source files are available on android")
 	}
+	if runtime.GOOS != "linux" || isRace {
+		t.Skip("currently uses too much memory, see issue #31611")
+	}
 	dir, err := os.Getwd()
 	if err != nil {
 		t.Errorf("could not get wd: %v", err)
@@ -64,53 +58,28 @@
 	}
 }
 
-func (l definitions) godef(src, def span.Span) {
-	l[src] = definition{
-		src:     src,
-		def:     def,
-		pattern: newPattern("", def),
-	}
-}
-
-func (l definitions) typdef(src, def span.Span) {
-	l[src] = definition{
-		src:     src,
-		def:     def,
-		pattern: newPattern("", def),
-	}
-}
-
-func (l definitions) definition(src span.Span, flags string, def span.Span, match string) {
-	l[src] = definition{
-		src:     src,
-		flags:   flags,
-		def:     def,
-		pattern: newPattern(match, def),
-	}
-}
-
-func (l definitions) testDefinitions(t *testing.T, e *packagestest.Exported) {
-	if len(l) != expectedDefinitionsCount {
-		t.Errorf("got %v definitions expected %v", len(l), expectedDefinitionsCount)
-	}
-	for _, d := range l {
+func (r *runner) Definition(t *testing.T, data tests.Definitions) {
+	for _, d := range data {
+		if d.IsType {
+			// TODO: support type definition queries
+			continue
+		}
 		args := []string{"query"}
-		if d.flags != "" {
-			args = append(args, strings.Split(d.flags, " ")...)
+		if d.Flags != "" {
+			args = append(args, strings.Split(d.Flags, " ")...)
 		}
 		args = append(args, "definition")
-		src := span.New(d.src.URI(), span.NewPoint(0, 0, d.src.Start().Offset()), span.Point{})
+		src := span.New(d.Src.URI(), span.NewPoint(0, 0, d.Src.Start().Offset()), span.Point{})
 		args = append(args, fmt.Sprint(src))
-		app := &cmd.Application{}
-		app.Config = *e.Config
 		got := captureStdOut(t, func() {
-			tool.Main(context.Background(), app, args)
+			tool.Main(context.Background(), r.app, args)
 		})
-		if !d.pattern.matches(got) {
-			t.Errorf("definition %v\nexpected:\n%s\ngot:\n%s", args, d.pattern, got)
+		pattern := newPattern(d.Match, d.Def)
+		if !pattern.matches(got) {
+			t.Errorf("definition %v\nexpected:\n%s\ngot:\n%s", args, pattern, got)
 		}
 		if *verifyGuru {
-			moduleMode := e.File(e.Modules[0].Name, "go.mod") != ""
+			moduleMode := r.data.Exported.File(r.data.Exported.Modules[0].Name, "go.mod") != ""
 			var guruArgs []string
 			runGuru := false
 			if !moduleMode {
@@ -133,14 +102,14 @@
 			}
 			if runGuru {
 				cmd := exec.Command("guru", guruArgs...)
-				cmd.Env = e.Config.Env
+				cmd.Env = r.data.Exported.Config.Env
 				out, err := cmd.CombinedOutput()
 				if err != nil {
 					t.Errorf("Could not run guru %v: %v\n%s", guruArgs, err, out)
 				} else {
 					guru := strings.TrimSpace(string(out))
-					if !d.pattern.matches(guru) {
-						t.Errorf("definition %v\nexpected:\n%s\nguru gave:\n%s", args, d.pattern, guru)
+					if !pattern.matches(guru) {
+						t.Errorf("definition %v\nexpected:\n%s\nguru gave:\n%s", args, pattern, guru)
 					}
 				}
 			}
@@ -148,13 +117,6 @@
 	}
 }
 
-func (l definitions) testTypeDefinitions(t *testing.T, e *packagestest.Exported) {
-	if len(l) != expectedTypeDefinitionsCount {
-		t.Errorf("got %v definitions expected %v", len(l), expectedTypeDefinitionsCount)
-	}
-	//TODO: add command line type definition tests when it works
-}
-
 type pattern struct {
 	raw      string
 	expanded []string
diff --git a/internal/lsp/lsp_test.go b/internal/lsp/lsp_test.go
index 44b3994..b9d0c27 100644
--- a/internal/lsp/lsp_test.go
+++ b/internal/lsp/lsp_test.go
@@ -8,13 +8,7 @@
 	"bytes"
 	"context"
 	"fmt"
-	"go/ast"
-	"go/parser"
 	"go/token"
-	"io/ioutil"
-	"os/exec"
-	"path/filepath"
-	"runtime"
 	"sort"
 	"strings"
 	"testing"
@@ -24,6 +18,7 @@
 	"golang.org/x/tools/internal/lsp/diff"
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/tests"
 	"golang.org/x/tools/internal/lsp/xlog"
 	"golang.org/x/tools/internal/span"
 )
@@ -32,246 +27,47 @@
 	packagestest.TestAll(t, testLSP)
 }
 
+type runner struct {
+	server *Server
+	data   *tests.Data
+}
+
 func testLSP(t *testing.T, exporter packagestest.Exporter) {
 	ctx := context.Background()
-	const dir = "testdata"
 
-	// We hardcode the expected number of test cases to ensure that all tests
-	// are being executed. If a test is added, this number must be changed.
-	const expectedCompletionsCount = 65
-	const expectedDiagnosticsCount = 16
-	const expectedFormatCount = 4
-	const expectedDefinitionsCount = 19
-	const expectedTypeDefinitionsCount = 2
-	const expectedHighlightsCount = 2
-	const expectedSymbolsCount = 1
-	const expectedSignaturesCount = 19
-
-	files := packagestest.MustCopyFileTree(dir)
-	overlays := map[string][]byte{}
-	for fragment, operation := range files {
-		if trimmed := strings.TrimSuffix(fragment, ".in"); trimmed != fragment {
-			delete(files, fragment)
-			files[trimmed] = operation
-		}
-		const overlay = ".overlay"
-		if index := strings.Index(fragment, overlay); index >= 0 {
-			delete(files, fragment)
-			partial := fragment[:index] + fragment[index+len(overlay):]
-			contents, err := ioutil.ReadFile(filepath.Join(dir, fragment))
-			if err != nil {
-				t.Fatal(err)
-			}
-			overlays[partial] = contents
-		}
-	}
-	modules := []packagestest.Module{
-		{
-			Name:    "golang.org/x/tools/internal/lsp",
-			Files:   files,
-			Overlay: overlays,
-		},
-	}
-	exported := packagestest.Export(t, exporter, modules)
-	defer exported.Cleanup()
-
-	// Merge the exported.Config with the view.Config.
-	cfg := *exported.Config
-
-	cfg.Fset = token.NewFileSet()
-	cfg.Context = context.Background()
-	cfg.ParseFile = func(fset *token.FileSet, filename string, src []byte) (*ast.File, error) {
-		return parser.ParseFile(fset, filename, src, parser.AllErrors|parser.ParseComments)
-	}
+	data := tests.Load(t, exporter, "testdata")
+	defer data.Exported.Cleanup()
 
 	log := xlog.New(xlog.StdSink{})
-	s := &Server{
-		views:       []*cache.View{cache.NewView(ctx, log, "lsp_test", span.FileURI(cfg.Dir), &cfg)},
-		undelivered: make(map[span.URI][]source.Diagnostic),
-		log:         log,
-	}
-	// Do a first pass to collect special markers for completion.
-	if err := exported.Expect(map[string]interface{}{
-		"item": func(name string, r packagestest.Range, _, _ string) {
-			exported.Mark(name, r)
+	r := &runner{
+		server: &Server{
+			views:       []*cache.View{cache.NewView(ctx, log, "lsp_test", span.FileURI(data.Config.Dir), &data.Config)},
+			undelivered: make(map[span.URI][]source.Diagnostic),
+			log:         log,
 		},
-	}); err != nil {
-		t.Fatal(err)
+		data: data,
 	}
-
-	expectedDiagnostics := make(diagnostics)
-	completionItems := make(completionItems)
-	expectedCompletions := make(completions)
-	expectedFormat := make(formats)
-	expectedDefinitions := make(definitions)
-	expectedTypeDefinitions := make(definitions)
-	expectedHighlights := make(highlights)
-	expectedSymbols := &symbols{
-		m:        make(map[span.URI][]protocol.DocumentSymbol),
-		children: make(map[string][]protocol.DocumentSymbol),
-	}
-	expectedSignatures := make(signatures)
-
-	// Collect any data that needs to be used by subsequent tests.
-	if err := exported.Expect(map[string]interface{}{
-		"diag":      expectedDiagnostics.collect,
-		"item":      completionItems.collect,
-		"complete":  expectedCompletions.collect,
-		"format":    expectedFormat.collect,
-		"godef":     expectedDefinitions.collect,
-		"typdef":    expectedTypeDefinitions.collect,
-		"highlight": expectedHighlights.collect,
-		"symbol":    expectedSymbols.collect,
-		"signature": expectedSignatures.collect,
-	}); err != nil {
-		t.Fatal(err)
-	}
-
-	t.Run("Completion", func(t *testing.T) {
-		t.Helper()
-		if len(expectedCompletions) != expectedCompletionsCount {
-			t.Errorf("got %v completions expected %v", len(expectedCompletions), expectedCompletionsCount)
-		}
-		expectedCompletions.test(t, exported, s, completionItems)
-	})
-
-	t.Run("Diagnostics", func(t *testing.T) {
-		t.Helper()
-		diagnosticsCount := expectedDiagnostics.test(t, s.views[0])
-		if diagnosticsCount != expectedDiagnosticsCount {
-			t.Errorf("got %v diagnostics expected %v", diagnosticsCount, expectedDiagnosticsCount)
-		}
-	})
-
-	t.Run("Format", func(t *testing.T) {
-		if _, err := exec.LookPath("gofmt"); err != nil {
-			switch runtime.GOOS {
-			case "android":
-				t.Skip("gofmt is not installed")
-			default:
-				t.Fatal(err)
-			}
-		}
-		t.Helper()
-		if len(expectedFormat) != expectedFormatCount {
-			t.Errorf("got %v formats expected %v", len(expectedFormat), expectedFormatCount)
-		}
-		expectedFormat.test(t, s)
-	})
-
-	t.Run("Definitions", func(t *testing.T) {
-		t.Helper()
-		if len(expectedDefinitions) != expectedDefinitionsCount {
-			t.Errorf("got %v definitions expected %v", len(expectedDefinitions), expectedDefinitionsCount)
-		}
-		expectedDefinitions.test(t, s, false)
-	})
-
-	t.Run("TypeDefinitions", func(t *testing.T) {
-		t.Helper()
-		if len(expectedTypeDefinitions) != expectedTypeDefinitionsCount {
-			t.Errorf("got %v type definitions expected %v", len(expectedTypeDefinitions), expectedTypeDefinitionsCount)
-		}
-		expectedTypeDefinitions.test(t, s, true)
-	})
-
-	t.Run("Highlights", func(t *testing.T) {
-		t.Helper()
-		if len(expectedHighlights) != expectedHighlightsCount {
-			t.Errorf("got %v highlights expected %v", len(expectedHighlights), expectedHighlightsCount)
-		}
-		expectedHighlights.test(t, s)
-	})
-
-	t.Run("Symbols", func(t *testing.T) {
-		t.Helper()
-		if len(expectedSymbols.m) != expectedSymbolsCount {
-			t.Errorf("got %v symbols expected %v", len(expectedSymbols.m), expectedSymbolsCount)
-		}
-		expectedSymbols.test(t, s)
-	})
-
-	t.Run("Signatures", func(t *testing.T) {
-		t.Helper()
-		if len(expectedSignatures) != expectedSignaturesCount {
-			t.Errorf("got %v signatures expected %v", len(expectedSignatures), expectedSignaturesCount)
-		}
-		expectedSignatures.test(t, s)
-	})
+	tests.Run(t, r, data)
 }
 
-type diagnostics map[span.URI][]protocol.Diagnostic
-type completionItems map[token.Pos]*protocol.CompletionItem
-type completions map[token.Position][]token.Pos
-type formats map[string]string
-type definitions map[protocol.Location]protocol.Location
-type highlights map[string][]protocol.Location
-type symbols struct {
-	m        map[span.URI][]protocol.DocumentSymbol
-	children map[string][]protocol.DocumentSymbol
-}
-type signatures map[token.Position]*protocol.SignatureHelp
-
-func (d diagnostics) test(t *testing.T, v source.View) int {
-	count := 0
-	ctx := context.Background()
-	for uri, want := range d {
-		sourceDiagnostics, err := source.Diagnostics(context.Background(), v, uri)
+func (r *runner) Diagnostics(t *testing.T, data tests.Diagnostics) {
+	v := r.server.views[0]
+	for uri, want := range data {
+		results, err := source.Diagnostics(context.Background(), v, uri)
 		if err != nil {
 			t.Fatal(err)
 		}
-		got, err := toProtocolDiagnostics(ctx, v, sourceDiagnostics[uri])
-		if err != nil {
-			t.Fatal(err)
-		}
+		got := results[uri]
 		if diff := diffDiagnostics(uri, want, got); diff != "" {
 			t.Error(diff)
 		}
-		count += len(want)
 	}
-	return count
 }
 
-func (d diagnostics) collect(e *packagestest.Exported, fset *token.FileSet, rng packagestest.Range, msgSource, msg string) {
-	spn, m := testLocation(e, fset, rng)
-	if _, ok := d[spn.URI()]; !ok {
-		d[spn.URI()] = []protocol.Diagnostic{}
-	}
-	// If a file has an empty diagnostic message, return. This allows us to
-	// avoid testing diagnostics in files that may have a lot of them.
-	if msg == "" {
-		return
-	}
-	severity := protocol.SeverityError
-	if strings.Contains(string(spn.URI()), "analyzer") {
-		severity = protocol.SeverityWarning
-	}
-	dRng, err := m.Range(spn)
-	if err != nil {
-		return
-	}
-	want := protocol.Diagnostic{
-		Range:    dRng,
-		Severity: severity,
-		Source:   msgSource,
-		Message:  msg,
-	}
-	d[spn.URI()] = append(d[spn.URI()], want)
-}
-
-func sortDiagnostics(d []protocol.Diagnostic) {
+func sortDiagnostics(d []source.Diagnostic) {
 	sort.Slice(d, func(i int, j int) bool {
-		if d[i].Range.Start.Line < d[j].Range.Start.Line {
-			return true
-		}
-		if d[i].Range.Start.Line > d[j].Range.Start.Line {
-			return false
-		}
-		if d[i].Range.Start.Character < d[j].Range.Start.Character {
-			return true
-		}
-		if d[i].Range.Start.Character > d[j].Range.Start.Character {
-			return false
+		if r := span.Compare(d[i].Span, d[j].Span); r != 0 {
+			return r < 0
 		}
 		return d[i].Message < d[j].Message
 	})
@@ -279,7 +75,7 @@
 
 // diffDiagnostics prints the diff between expected and actual diagnostics test
 // results.
-func diffDiagnostics(uri span.URI, want, got []protocol.Diagnostic) string {
+func diffDiagnostics(uri span.URI, want, got []source.Diagnostic) string {
 	sortDiagnostics(want)
 	sortDiagnostics(got)
 	if len(got) != len(want) {
@@ -290,17 +86,17 @@
 		if w.Message != g.Message {
 			return summarizeDiagnostics(i, want, got, "incorrect Message got %v want %v", g.Message, w.Message)
 		}
-		if w.Range.Start != g.Range.Start {
-			return summarizeDiagnostics(i, want, got, "incorrect Range.Start got %v want %v", g.Range.Start, w.Range.Start)
+		if span.ComparePoint(w.Start(), g.Start()) != 0 {
+			return summarizeDiagnostics(i, want, got, "incorrect Start got %v want %v", g.Start(), w.Start())
 		}
 		// Special case for diagnostics on parse errors.
 		if strings.Contains(string(uri), "noparse") {
-			if g.Range.Start != g.Range.End || w.Range.Start != g.Range.End {
-				return summarizeDiagnostics(i, want, got, "incorrect Range.End got %v want %v", g.Range.End, w.Range.Start)
+			if span.ComparePoint(g.Start(), g.End()) != 0 || span.ComparePoint(w.Start(), g.End()) != 0 {
+				return summarizeDiagnostics(i, want, got, "incorrect End got %v want %v", g.End(), w.Start())
 			}
-		} else if g.Range.End != g.Range.Start { // Accept any 'want' range if the diagnostic returns a zero-length range.
-			if w.Range.End != g.Range.End {
-				return summarizeDiagnostics(i, want, got, "incorrect Range.End got %v want %v", g.Range.End, w.Range.End)
+		} else if !g.IsPoint() { // Accept any 'want' range if the diagnostic returns a zero-length range.
+			if span.ComparePoint(w.End(), g.End()) != 0 {
+				return summarizeDiagnostics(i, want, got, "incorrect End got %v want %v", g.End(), w.End())
 			}
 		}
 		if w.Severity != g.Severity {
@@ -313,7 +109,7 @@
 	return ""
 }
 
-func summarizeDiagnostics(i int, want []protocol.Diagnostic, got []protocol.Diagnostic, reason string, args ...interface{}) string {
+func summarizeDiagnostics(i int, want []source.Diagnostic, got []source.Diagnostic, reason string, args ...interface{}) string {
 	msg := &bytes.Buffer{}
 	fmt.Fprint(msg, "diagnostics failed")
 	if i >= 0 {
@@ -332,27 +128,27 @@
 	return msg.String()
 }
 
-func (c completions) test(t *testing.T, exported *packagestest.Exported, s *Server, items completionItems) {
-	for src, itemList := range c {
-		var want []protocol.CompletionItem
+func (r *runner) Completion(t *testing.T, data tests.Completions, items tests.CompletionItems) {
+	for src, itemList := range data {
+		var want []source.CompletionItem
 		for _, pos := range itemList {
 			want = append(want, *items[pos])
 		}
-		list, err := s.Completion(context.Background(), &protocol.CompletionParams{
+		list, err := r.server.Completion(context.Background(), &protocol.CompletionParams{
 			TextDocumentPositionParams: protocol.TextDocumentPositionParams{
 				TextDocument: protocol.TextDocumentIdentifier{
-					URI: protocol.NewURI(span.FileURI(src.Filename)),
+					URI: protocol.NewURI(src.URI()),
 				},
 				Position: protocol.Position{
-					Line:      float64(src.Line - 1),
-					Character: float64(src.Column - 1),
+					Line:      float64(src.Start().Line() - 1),
+					Character: float64(src.Start().Column() - 1),
 				},
 			},
 		})
 		if err != nil {
 			t.Fatal(err)
 		}
-		wantBuiltins := strings.Contains(src.Filename, "builtins")
+		wantBuiltins := strings.Contains(string(src.URI()), "builtins")
 		var got []protocol.CompletionItem
 		for _, item := range list.Items {
 			if !wantBuiltins && isBuiltin(item) {
@@ -361,7 +157,7 @@
 			got = append(got, item)
 		}
 		if err != nil {
-			t.Fatalf("completion failed for %s:%v:%v: %v", filepath.Base(src.Filename), src.Line, src.Column, err)
+			t.Fatalf("completion failed for %v: %v", src, err)
 		}
 		if diff := diffCompletionItems(t, src, want, got); diff != "" {
 			t.Errorf(diff)
@@ -388,21 +184,9 @@
 	return false
 }
 
-func (c completions) collect(src token.Position, expected []token.Pos) {
-	c[src] = expected
-}
-
-func (i completionItems) collect(pos token.Pos, label, detail, kind string) {
-	i[pos] = &protocol.CompletionItem{
-		Label:  label,
-		Detail: detail,
-		Kind:   protocol.ParseCompletionItemKind(kind),
-	}
-}
-
 // diffCompletionItems prints the diff between expected and actual completion
 // test results.
-func diffCompletionItems(t *testing.T, pos token.Position, want, got []protocol.CompletionItem) string {
+func diffCompletionItems(t *testing.T, spn span.Span, want []source.CompletionItem, got []protocol.CompletionItem) string {
 	if len(got) != len(want) {
 		return summarizeCompletionItems(-1, want, got, "different lengths got %v want %v", len(got), len(want))
 	}
@@ -414,14 +198,14 @@
 		if w.Detail != g.Detail {
 			return summarizeCompletionItems(i, want, got, "incorrect Detail got %v want %v", g.Detail, w.Detail)
 		}
-		if w.Kind != g.Kind {
-			return summarizeCompletionItems(i, want, got, "incorrect Kind got %v want %v", g.Kind, w.Kind)
+		if wkind := toProtocolCompletionItemKind(w.Kind); wkind != g.Kind {
+			return summarizeCompletionItems(i, want, got, "incorrect Kind got %v want %v", g.Kind, wkind)
 		}
 	}
 	return ""
 }
 
-func summarizeCompletionItems(i int, want []protocol.CompletionItem, got []protocol.CompletionItem, reason string, args ...interface{}) string {
+func summarizeCompletionItems(i int, want []source.CompletionItem, got []protocol.CompletionItem, reason string, args ...interface{}) string {
 	msg := &bytes.Buffer{}
 	fmt.Fprint(msg, "completion failed")
 	if i >= 0 {
@@ -440,11 +224,11 @@
 	return msg.String()
 }
 
-func (f formats) test(t *testing.T, s *Server) {
+func (r *runner) Format(t *testing.T, data tests.Formats) {
 	ctx := context.Background()
-	for filename, gofmted := range f {
+	for filename, gofmted := range data {
 		uri := span.FileURI(filename)
-		edits, err := s.Formatting(context.Background(), &protocol.DocumentFormattingParams{
+		edits, err := r.server.Formatting(context.Background(), &protocol.DocumentFormattingParams{
 			TextDocument: protocol.TextDocumentIdentifier{
 				URI: protocol.NewURI(uri),
 			},
@@ -455,7 +239,7 @@
 			}
 			continue
 		}
-		_, m, err := newColumnMap(ctx, s.findView(ctx, uri), uri)
+		_, m, err := newColumnMap(ctx, r.server.findView(ctx, uri), uri)
 		if err != nil {
 			t.Error(err)
 		}
@@ -471,74 +255,51 @@
 	}
 }
 
-func (f formats) collect(pos token.Position) {
-	cmd := exec.Command("gofmt", pos.Filename)
-	stdout := bytes.NewBuffer(nil)
-	cmd.Stdout = stdout
-	cmd.Run() // ignore error, sometimes we have intentionally ungofmt-able files
-	f[pos.Filename] = stdout.String()
-}
-
-func (d definitions) test(t *testing.T, s *Server, typ bool) {
-	for src, target := range d {
+func (r *runner) Definition(t *testing.T, data tests.Definitions) {
+	for _, d := range data {
+		sm := r.mapper(d.Src.URI())
+		loc, err := sm.Location(d.Src)
+		if err != nil {
+			t.Fatalf("failed for %v: %v", d.Src, err)
+		}
 		params := &protocol.TextDocumentPositionParams{
-			TextDocument: protocol.TextDocumentIdentifier{
-				URI: src.URI,
-			},
-			Position: src.Range.Start,
+			TextDocument: protocol.TextDocumentIdentifier{URI: loc.URI},
+			Position:     loc.Range.Start,
 		}
 		var locs []protocol.Location
-		var err error
-		if typ {
-			locs, err = s.TypeDefinition(context.Background(), params)
+		if d.IsType {
+			locs, err = r.server.TypeDefinition(context.Background(), params)
 		} else {
-			locs, err = s.Definition(context.Background(), params)
+			locs, err = r.server.Definition(context.Background(), params)
 		}
 		if err != nil {
-			t.Fatalf("failed for %v: %v", src, err)
+			t.Fatalf("failed for %v: %v", d.Src, err)
 		}
 		if len(locs) != 1 {
 			t.Errorf("got %d locations for definition, expected 1", len(locs))
 		}
-		if locs[0] != target {
-			t.Errorf("for %v got %v want %v", src, locs[0], target)
+		locURI := span.NewURI(locs[0].URI)
+		lm := r.mapper(locURI)
+		if def, err := lm.Span(locs[0]); err != nil {
+			t.Fatalf("failed for %v: %v", locs[0], err)
+		} else if def != d.Def {
+			t.Errorf("for %v got %v want %v", d.Src, def, d.Def)
 		}
 	}
 }
 
-func (d definitions) collect(e *packagestest.Exported, fset *token.FileSet, src, target packagestest.Range) {
-	sSrc, mSrc := testLocation(e, fset, src)
-	lSrc, err := mSrc.Location(sSrc)
-	if err != nil {
-		return
-	}
-	sTarget, mTarget := testLocation(e, fset, target)
-	lTarget, err := mTarget.Location(sTarget)
-	if err != nil {
-		return
-	}
-	d[lSrc] = lTarget
-}
-
-func (h highlights) collect(e *packagestest.Exported, fset *token.FileSet, name string, rng packagestest.Range) {
-	s, m := testLocation(e, fset, rng)
-	loc, err := m.Location(s)
-	if err != nil {
-		return
-	}
-
-	h[name] = append(h[name], loc)
-}
-
-func (h highlights) test(t *testing.T, s *Server) {
-	for name, locations := range h {
+func (r *runner) Highlight(t *testing.T, data tests.Highlights) {
+	for name, locations := range data {
+		m := r.mapper(locations[0].URI())
+		loc, err := m.Location(locations[0])
+		if err != nil {
+			t.Fatalf("failed for %v: %v", locations[0], err)
+		}
 		params := &protocol.TextDocumentPositionParams{
-			TextDocument: protocol.TextDocumentIdentifier{
-				URI: locations[0].URI,
-			},
-			Position: locations[0].Range.Start,
+			TextDocument: protocol.TextDocumentIdentifier{URI: loc.URI},
+			Position:     loc.Range.Start,
 		}
-		highlights, err := s.DocumentHighlight(context.Background(), params)
+		highlights, err := r.server.DocumentHighlight(context.Background(), params)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -546,55 +307,23 @@
 			t.Fatalf("got %d highlights for %s, expected %d", len(highlights), name, len(locations))
 		}
 		for i := range highlights {
-			if highlights[i].Range != locations[i].Range {
-				t.Errorf("want %v, got %v\n", locations[i].Range, highlights[i].Range)
+			if h, err := m.RangeSpan(highlights[i].Range); err != nil {
+				t.Fatalf("failed for %v: %v", highlights[i], err)
+			} else if h != locations[i] {
+				t.Errorf("want %v, got %v\n", locations[i], h)
 			}
 		}
 	}
 }
 
-func (s symbols) collect(e *packagestest.Exported, fset *token.FileSet, name string, rng span.Range, kind string, parentName string) {
-	f := fset.File(rng.Start)
-	if f == nil {
-		return
-	}
-
-	content, err := e.FileContents(f.Name())
-	if err != nil {
-		return
-	}
-
-	spn, err := rng.Span()
-	if err != nil {
-		return
-	}
-
-	m := protocol.NewColumnMapper(spn.URI(), fset, f, content)
-	prng, err := m.Range(spn)
-	if err != nil {
-		return
-	}
-
-	sym := protocol.DocumentSymbol{
-		Name:           name,
-		Kind:           protocol.ParseSymbolKind(kind),
-		SelectionRange: prng,
-	}
-	if parentName == "" {
-		s.m[spn.URI()] = append(s.m[spn.URI()], sym)
-	} else {
-		s.children[parentName] = append(s.children[parentName], sym)
-	}
-}
-
-func (s symbols) test(t *testing.T, server *Server) {
-	for uri, expectedSymbols := range s.m {
+func (r *runner) Symbol(t *testing.T, data tests.Symbols) {
+	for uri, expectedSymbols := range data {
 		params := &protocol.DocumentSymbolParams{
 			TextDocument: protocol.TextDocumentIdentifier{
 				URI: string(uri),
 			},
 		}
-		symbols, err := server.DocumentSymbol(context.Background(), params)
+		symbols, err := r.server.DocumentSymbol(context.Background(), params)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -603,86 +332,16 @@
 			t.Errorf("want %d top-level symbols in %v, got %d", len(expectedSymbols), uri, len(symbols))
 			continue
 		}
-
-		for i := range expectedSymbols {
-			children := s.children[expectedSymbols[i].Name]
-			expectedSymbols[i].Children = children
-		}
-		if diff := diffSymbols(uri, expectedSymbols, symbols); diff != "" {
+		if diff := r.diffSymbols(uri, expectedSymbols, symbols); diff != "" {
 			t.Error(diff)
 		}
 	}
 }
 
-func (s signatures) collect(src token.Position, signature string, activeParam int64) {
-	s[src] = &protocol.SignatureHelp{
-		Signatures:      []protocol.SignatureInformation{{Label: signature}},
-		ActiveSignature: 0,
-		ActiveParameter: float64(activeParam),
-	}
-}
-
-func diffSignatures(src token.Position, want, got *protocol.SignatureHelp) string {
-	decorate := func(f string, args ...interface{}) string {
-		return fmt.Sprintf("Invalid signature at %s: %s", src, fmt.Sprintf(f, args...))
-	}
-
-	if lw, lg := len(want.Signatures), len(got.Signatures); lw != lg {
-		return decorate("wanted %d signatures, got %d", lw, lg)
-	}
-
-	if want.ActiveSignature != got.ActiveSignature {
-		return decorate("wanted active signature of %f, got %f", want.ActiveSignature, got.ActiveSignature)
-	}
-
-	if want.ActiveParameter != got.ActiveParameter {
-		return decorate("wanted active parameter of %f, got %f", want.ActiveParameter, got.ActiveParameter)
-	}
-
-	for i := range want.Signatures {
-		wantSig, gotSig := want.Signatures[i], got.Signatures[i]
-
-		if wantSig.Label != gotSig.Label {
-			return decorate("wanted label %q, got %q", wantSig.Label, gotSig.Label)
-		}
-
-		var paramParts []string
-		for _, p := range gotSig.Parameters {
-			paramParts = append(paramParts, p.Label)
-		}
-		paramsStr := strings.Join(paramParts, ", ")
-		if !strings.Contains(gotSig.Label, paramsStr) {
-			return decorate("expected signature %q to contain params %q", gotSig.Label, paramsStr)
-		}
-	}
-
-	return ""
-}
-
-func (s signatures) test(t *testing.T, server *Server) {
-	for src, expectedSignatures := range s {
-		gotSignatures, err := server.SignatureHelp(context.Background(), &protocol.TextDocumentPositionParams{
-			TextDocument: protocol.TextDocumentIdentifier{
-				URI: protocol.NewURI(span.FileURI(src.Filename)),
-			},
-			Position: protocol.Position{
-				Line:      float64(src.Line - 1),
-				Character: float64(src.Column - 1),
-			},
-		})
-		if err != nil {
-			t.Fatal(err)
-		}
-
-		if diff := diffSignatures(src, expectedSignatures, gotSignatures); diff != "" {
-			t.Error(diff)
-		}
-	}
-}
-
-func diffSymbols(uri span.URI, want, got []protocol.DocumentSymbol) string {
+func (r *runner) diffSymbols(uri span.URI, want []source.Symbol, got []protocol.DocumentSymbol) string {
 	sort.Slice(want, func(i, j int) bool { return want[i].Name < want[j].Name })
 	sort.Slice(got, func(i, j int) bool { return got[i].Name < got[j].Name })
+	m := r.mapper(uri)
 	if len(got) != len(want) {
 		return summarizeSymbols(-1, want, got, "different lengths got %v want %v", len(got), len(want))
 	}
@@ -691,20 +350,24 @@
 		if w.Name != g.Name {
 			return summarizeSymbols(i, want, got, "incorrect name got %v want %v", g.Name, w.Name)
 		}
-		if w.Kind != g.Kind {
-			return summarizeSymbols(i, want, got, "incorrect kind got %v want %v", g.Kind, w.Kind)
+		if wkind := toProtocolSymbolKind(w.Kind); wkind != g.Kind {
+			return summarizeSymbols(i, want, got, "incorrect kind got %v want %v", g.Kind, wkind)
 		}
-		if w.SelectionRange != g.SelectionRange {
-			return summarizeSymbols(i, want, got, "incorrect span got %v want %v", g.SelectionRange, w.SelectionRange)
+		spn, err := m.RangeSpan(g.SelectionRange)
+		if err != nil {
+			return summarizeSymbols(i, want, got, "%v", err)
 		}
-		if msg := diffSymbols(uri, w.Children, g.Children); msg != "" {
+		if w.SelectionSpan != spn {
+			return summarizeSymbols(i, want, got, "incorrect span got %v want %v", spn, w.SelectionSpan)
+		}
+		if msg := r.diffSymbols(uri, w.Children, g.Children); msg != "" {
 			return fmt.Sprintf("children of %s: %s", w.Name, msg)
 		}
 	}
 	return ""
 }
 
-func summarizeSymbols(i int, want []protocol.DocumentSymbol, got []protocol.DocumentSymbol, reason string, args ...interface{}) string {
+func summarizeSymbols(i int, want []source.Symbol, got []protocol.DocumentSymbol, reason string, args ...interface{}) string {
 	msg := &bytes.Buffer{}
 	fmt.Fprint(msg, "document symbols failed")
 	if i >= 0 {
@@ -714,7 +377,7 @@
 	fmt.Fprintf(msg, reason, args...)
 	fmt.Fprint(msg, ":\nexpected:\n")
 	for _, s := range want {
-		fmt.Fprintf(msg, "  %v %v %v\n", s.Name, s.Kind, s.SelectionRange)
+		fmt.Fprintf(msg, "  %v %v %v\n", s.Name, s.Kind, s.SelectionSpan)
 	}
 	fmt.Fprintf(msg, "got:\n")
 	for _, s := range got {
@@ -723,18 +386,86 @@
 	return msg.String()
 }
 
-func testLocation(e *packagestest.Exported, fset *token.FileSet, rng packagestest.Range) (span.Span, *protocol.ColumnMapper) {
-	spn, err := span.NewRange(fset, rng.Start, rng.End).Span()
-	if err != nil {
-		return spn, nil
+func (r *runner) Signature(t *testing.T, data tests.Signatures) {
+	for spn, expectedSignatures := range data {
+		m := r.mapper(spn.URI())
+		loc, err := m.Location(spn)
+		if err != nil {
+			t.Fatalf("failed for %v: %v", loc, err)
+		}
+		gotSignatures, err := r.server.SignatureHelp(context.Background(), &protocol.TextDocumentPositionParams{
+			TextDocument: protocol.TextDocumentIdentifier{
+				URI: protocol.NewURI(spn.URI()),
+			},
+			Position: loc.Range.Start,
+		})
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if diff := diffSignatures(spn, expectedSignatures, gotSignatures); diff != "" {
+			t.Error(diff)
+		}
 	}
-	f := fset.File(rng.Start)
-	content, err := e.FileContents(f.Name())
-	if err != nil {
-		return spn, nil
+}
+
+func diffSignatures(spn span.Span, want source.SignatureInformation, got *protocol.SignatureHelp) string {
+	decorate := func(f string, args ...interface{}) string {
+		return fmt.Sprintf("Invalid signature at %s: %s", spn, fmt.Sprintf(f, args...))
 	}
-	m := protocol.NewColumnMapper(spn.URI(), fset, f, content)
-	return spn, m
+
+	if len(got.Signatures) != 1 {
+		return decorate("wanted 1 signature, got %d", len(got.Signatures))
+	}
+
+	if got.ActiveSignature != 0 {
+		return decorate("wanted active signature of 0, got %f", got.ActiveSignature)
+	}
+
+	if want.ActiveParameter != int(got.ActiveParameter) {
+		return decorate("wanted active parameter of %d, got %f", want.ActiveParameter, got.ActiveParameter)
+	}
+
+	gotSig := got.Signatures[int(got.ActiveSignature)]
+
+	if want.Label != gotSig.Label {
+		return decorate("wanted label %q, got %q", want.Label, gotSig.Label)
+	}
+
+	var paramParts []string
+	for _, p := range gotSig.Parameters {
+		paramParts = append(paramParts, p.Label)
+	}
+	paramsStr := strings.Join(paramParts, ", ")
+	if !strings.Contains(gotSig.Label, paramsStr) {
+		return decorate("expected signature %q to contain params %q", gotSig.Label, paramsStr)
+	}
+
+	return ""
+}
+
+func (r *runner) mapper(uri span.URI) *protocol.ColumnMapper {
+	fname, err := uri.Filename()
+	if err != nil {
+		return nil
+	}
+	fset := r.data.Exported.ExpectFileSet
+	var f *token.File
+	fset.Iterate(func(check *token.File) bool {
+		if check.Name() == fname {
+			f = check
+			return false
+		}
+		return true
+	})
+	if f == nil {
+		return nil
+	}
+	content, err := r.data.Exported.FileContents(f.Name())
+	if err != nil {
+		return nil
+	}
+	return protocol.NewColumnMapper(uri, fset, f, content)
 }
 
 func TestBytesOffset(t *testing.T) {
diff --git a/internal/lsp/tests/tests.go b/internal/lsp/tests/tests.go
new file mode 100644
index 0000000..10012c8
--- /dev/null
+++ b/internal/lsp/tests/tests.go
@@ -0,0 +1,313 @@
+// Copyright 2019q The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package tests
+
+import (
+	"bytes"
+	"context"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"io/ioutil"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+
+	"golang.org/x/tools/go/packages"
+	"golang.org/x/tools/go/packages/packagestest"
+	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/span"
+)
+
+// We hardcode the expected number of test cases to ensure that all tests
+// are being executed. If a test is added, this number must be changed.
+const (
+	ExpectedCompletionsCount     = 65
+	ExpectedDiagnosticsCount     = 16
+	ExpectedFormatCount          = 4
+	ExpectedDefinitionsCount     = 21
+	ExpectedTypeDefinitionsCount = 2
+	ExpectedHighlightsCount      = 2
+	ExpectedSymbolsCount         = 1
+	ExpectedSignaturesCount      = 19
+)
+
+type Diagnostics map[span.URI][]source.Diagnostic
+type CompletionItems map[token.Pos]*source.CompletionItem
+type Completions map[span.Span][]token.Pos
+type Formats map[string]string
+type Definitions map[span.Span]Definition
+type Highlights map[string][]span.Span
+type Symbols map[span.URI][]source.Symbol
+type SymbolsChildren map[string][]source.Symbol
+type Signatures map[span.Span]source.SignatureInformation
+
+type Data struct {
+	Config          packages.Config
+	Exported        *packagestest.Exported
+	Diagnostics     Diagnostics
+	CompletionItems CompletionItems
+	Completions     Completions
+	Formats         Formats
+	Definitions     Definitions
+	Highlights      Highlights
+	Symbols         Symbols
+	symbolsChildren SymbolsChildren
+	Signatures      Signatures
+}
+
+type Tests interface {
+	Diagnostics(*testing.T, Diagnostics)
+	Completion(*testing.T, Completions, CompletionItems)
+	Format(*testing.T, Formats)
+	Definition(*testing.T, Definitions)
+	Highlight(*testing.T, Highlights)
+	Symbol(*testing.T, Symbols)
+	Signature(*testing.T, Signatures)
+}
+
+type Definition struct {
+	Src    span.Span
+	IsType bool
+	Flags  string
+	Def    span.Span
+	Match  string
+}
+
+func Load(t testing.TB, exporter packagestest.Exporter, dir string) *Data {
+	t.Helper()
+
+	data := &Data{
+		Diagnostics:     make(Diagnostics),
+		CompletionItems: make(CompletionItems),
+		Completions:     make(Completions),
+		Formats:         make(Formats),
+		Definitions:     make(Definitions),
+		Highlights:      make(Highlights),
+		Symbols:         make(Symbols),
+		symbolsChildren: make(SymbolsChildren),
+		Signatures:      make(Signatures),
+	}
+
+	files := packagestest.MustCopyFileTree(dir)
+	overlays := map[string][]byte{}
+	for fragment, operation := range files {
+		if trimmed := strings.TrimSuffix(fragment, ".in"); trimmed != fragment {
+			delete(files, fragment)
+			files[trimmed] = operation
+		}
+		const overlay = ".overlay"
+		if index := strings.Index(fragment, overlay); index >= 0 {
+			delete(files, fragment)
+			partial := fragment[:index] + fragment[index+len(overlay):]
+			contents, err := ioutil.ReadFile(filepath.Join(dir, fragment))
+			if err != nil {
+				t.Fatal(err)
+			}
+			overlays[partial] = contents
+		}
+	}
+	modules := []packagestest.Module{
+		{
+			Name:    "golang.org/x/tools/internal/lsp",
+			Files:   files,
+			Overlay: overlays,
+		},
+	}
+	data.Exported = packagestest.Export(t, exporter, modules)
+
+	// Merge the exported.Config with the view.Config.
+	data.Config = *data.Exported.Config
+	data.Config.Fset = token.NewFileSet()
+	data.Config.Context = context.Background()
+	data.Config.ParseFile = func(fset *token.FileSet, filename string, src []byte) (*ast.File, error) {
+		return parser.ParseFile(fset, filename, src, parser.AllErrors|parser.ParseComments)
+	}
+
+	// Do a first pass to collect special markers for completion.
+	if err := data.Exported.Expect(map[string]interface{}{
+		"item": func(name string, r packagestest.Range, _, _ string) {
+			data.Exported.Mark(name, r)
+		},
+	}); err != nil {
+		t.Fatal(err)
+	}
+
+	// Collect any data that needs to be used by subsequent tests.
+	if err := data.Exported.Expect(map[string]interface{}{
+		"diag":      data.collectDiagnostics,
+		"item":      data.collectCompletionItems,
+		"complete":  data.collectCompletions,
+		"format":    data.collectFormats,
+		"godef":     data.collectDefinitions,
+		"typdef":    data.collectTypeDefinitions,
+		"highlight": data.collectHighlights,
+		"symbol":    data.collectSymbols,
+		"signature": data.collectSignatures,
+	}); err != nil {
+		t.Fatal(err)
+	}
+	for _, symbols := range data.Symbols {
+		for i := range symbols {
+			children := data.symbolsChildren[symbols[i].Name]
+			symbols[i].Children = children
+		}
+	}
+	return data
+}
+
+func Run(t *testing.T, tests Tests, data *Data) {
+	t.Helper()
+	t.Run("Completion", func(t *testing.T) {
+		t.Helper()
+		if len(data.Completions) != ExpectedCompletionsCount {
+			t.Errorf("got %v completions expected %v", len(data.Completions), ExpectedCompletionsCount)
+		}
+		tests.Completion(t, data.Completions, data.CompletionItems)
+	})
+
+	t.Run("Diagnostics", func(t *testing.T) {
+		t.Helper()
+		diagnosticsCount := 0
+		for _, want := range data.Diagnostics {
+			diagnosticsCount += len(want)
+		}
+		if diagnosticsCount != ExpectedDiagnosticsCount {
+			t.Errorf("got %v diagnostics expected %v", diagnosticsCount, ExpectedDiagnosticsCount)
+		}
+		tests.Diagnostics(t, data.Diagnostics)
+	})
+
+	t.Run("Format", func(t *testing.T) {
+		t.Helper()
+		if _, err := exec.LookPath("gofmt"); err != nil {
+			switch runtime.GOOS {
+			case "android":
+				t.Skip("gofmt is not installed")
+			default:
+				t.Fatal(err)
+			}
+		}
+		if len(data.Formats) != ExpectedFormatCount {
+			t.Errorf("got %v formats expected %v", len(data.Formats), ExpectedFormatCount)
+		}
+		tests.Format(t, data.Formats)
+	})
+
+	t.Run("Definitions", func(t *testing.T) {
+		t.Helper()
+		if len(data.Definitions) != ExpectedDefinitionsCount {
+			t.Errorf("got %v definitions expected %v", len(data.Definitions), ExpectedDefinitionsCount)
+		}
+		tests.Definition(t, data.Definitions)
+	})
+
+	t.Run("Highlights", func(t *testing.T) {
+		t.Helper()
+		if len(data.Highlights) != ExpectedHighlightsCount {
+			t.Errorf("got %v highlights expected %v", len(data.Highlights), ExpectedHighlightsCount)
+		}
+		tests.Highlight(t, data.Highlights)
+	})
+
+	t.Run("Symbols", func(t *testing.T) {
+		t.Helper()
+		if len(data.Symbols) != ExpectedSymbolsCount {
+			t.Errorf("got %v symbols expected %v", len(data.Symbols), ExpectedSymbolsCount)
+		}
+		tests.Symbol(t, data.Symbols)
+	})
+
+	t.Run("Signatures", func(t *testing.T) {
+		t.Helper()
+		if len(data.Signatures) != ExpectedSignaturesCount {
+			t.Errorf("got %v signatures expected %v", len(data.Signatures), ExpectedSignaturesCount)
+		}
+		tests.Signature(t, data.Signatures)
+	})
+}
+
+func (data *Data) collectDiagnostics(spn span.Span, msgSource, msg string) {
+	if _, ok := data.Diagnostics[spn.URI()]; !ok {
+		data.Diagnostics[spn.URI()] = []source.Diagnostic{}
+	}
+	// If a file has an empty diagnostic message, return. This allows us to
+	// avoid testing diagnostics in files that may have a lot of them.
+	if msg == "" {
+		return
+	}
+	severity := source.SeverityError
+	if strings.Contains(string(spn.URI()), "analyzer") {
+		severity = source.SeverityWarning
+	}
+	want := source.Diagnostic{
+		Span:     spn,
+		Severity: severity,
+		Source:   msgSource,
+		Message:  msg,
+	}
+	data.Diagnostics[spn.URI()] = append(data.Diagnostics[spn.URI()], want)
+}
+
+func (data *Data) collectCompletions(src span.Span, expected []token.Pos) {
+	data.Completions[src] = expected
+}
+
+func (data *Data) collectCompletionItems(pos token.Pos, label, detail, kind string) {
+	data.CompletionItems[pos] = &source.CompletionItem{
+		Label:  label,
+		Detail: detail,
+		Kind:   source.ParseCompletionItemKind(kind),
+	}
+}
+
+func (data *Data) collectFormats(pos token.Position) {
+	cmd := exec.Command("gofmt", pos.Filename)
+	stdout := bytes.NewBuffer(nil)
+	cmd.Stdout = stdout
+	cmd.Run() // ignore error, sometimes we have intentionally ungofmt-able files
+	data.Formats[pos.Filename] = stdout.String()
+}
+
+func (data *Data) collectDefinitions(src, target span.Span) {
+	data.Definitions[src] = Definition{
+		Src: src,
+		Def: target,
+	}
+}
+
+func (data *Data) collectTypeDefinitions(src, target span.Span) {
+	data.Definitions[src] = Definition{
+		Src:    src,
+		Def:    target,
+		IsType: true,
+	}
+}
+
+func (data *Data) collectHighlights(name string, rng span.Span) {
+	data.Highlights[name] = append(data.Highlights[name], rng)
+}
+
+func (data *Data) collectSymbols(name string, spn span.Span, kind string, parentName string) {
+	sym := source.Symbol{
+		Name:          name,
+		Kind:          source.ParseSymbolKind(kind),
+		SelectionSpan: spn,
+	}
+	if parentName == "" {
+		data.Symbols[spn.URI()] = append(data.Symbols[spn.URI()], sym)
+	} else {
+		data.symbolsChildren[parentName] = append(data.symbolsChildren[parentName], sym)
+	}
+}
+
+func (data *Data) collectSignatures(spn span.Span, signature string, activeParam int64) {
+	data.Signatures[spn] = source.SignatureInformation{
+		Label:           signature,
+		ActiveParameter: int(activeParam),
+	}
+}