diff --git a/go/packages/packagestest/expect.go b/go/packages/packagestest/expect.go
index 2ba785e..6b78f2c 100644
--- a/go/packages/packagestest/expect.go
+++ b/go/packages/packagestest/expect.go
@@ -254,6 +254,23 @@
 			}
 			return reflect.ValueOf(b), args, nil
 		}, nil
+	case pt.Kind() == reflect.Slice:
+		return func(n *expect.Note, args []interface{}) (reflect.Value, []interface{}, error) {
+			converter, err := e.buildConverter(pt.Elem())
+			if err != nil {
+				return reflect.Value{}, nil, err
+			}
+			result := reflect.MakeSlice(reflect.SliceOf(pt.Elem()), 0, len(args))
+			for range args {
+				value, remains, err := converter(n, args)
+				if err != nil {
+					return reflect.Value{}, nil, err
+				}
+				result = reflect.Append(result, value)
+				args = remains
+			}
+			return result, args, nil
+		}, nil
 	default:
 		return nil, fmt.Errorf("param has invalid type %v", pt)
 	}
diff --git a/internal/lsp/completion.go b/internal/lsp/completion.go
index 878793b..583822d 100644
--- a/internal/lsp/completion.go
+++ b/internal/lsp/completion.go
@@ -1,3 +1,7 @@
+// Copyright 2018 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 lsp
 
 import (
diff --git a/internal/lsp/diagnostics_test.go b/internal/lsp/diagnostics_test.go
deleted file mode 100644
index 5ac7018..0000000
--- a/internal/lsp/diagnostics_test.go
+++ /dev/null
@@ -1,110 +0,0 @@
-// Copyright 2018 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 lsp
-
-import (
-	"go/token"
-	"path/filepath"
-	"reflect"
-	"sort"
-	"strings"
-	"testing"
-
-	"golang.org/x/tools/go/packages"
-	"golang.org/x/tools/go/packages/packagestest"
-	"golang.org/x/tools/internal/lsp/protocol"
-	"golang.org/x/tools/internal/lsp/source"
-)
-
-func TestDiagnostics(t *testing.T) {
-	packagestest.TestAll(t, testDiagnostics)
-}
-
-func testDiagnostics(t *testing.T, exporter packagestest.Exporter) {
-	files := packagestest.MustCopyFileTree("testdata/diagnostics")
-	// TODO(rstambler): Stop hardcoding this if we have more files that don't parse.
-	files["noparse/noparse.go"] = packagestest.Copy("testdata/diagnostics/noparse/noparse.go.in")
-	modules := []packagestest.Module{
-		{
-			Name:  "golang.org/x/tools/internal/lsp",
-			Files: files,
-		},
-	}
-	exported := packagestest.Export(t, exporter, modules)
-	defer exported.Cleanup()
-
-	dirs := make(map[string]bool)
-	wants := make(map[string][]protocol.Diagnostic)
-	for _, module := range modules {
-		for fragment := range module.Files {
-			if !strings.HasSuffix(fragment, ".go") {
-				continue
-			}
-			filename := exporter.Filename(exported, module.Name, fragment)
-			wants[filename] = []protocol.Diagnostic{}
-			dirs[filepath.Dir(filename)] = true
-		}
-	}
-	err := exported.Expect(map[string]interface{}{
-		"diag": func(pos token.Position, msg string) {
-			line := float64(pos.Line - 1)
-			col := float64(pos.Column - 1)
-			want := protocol.Diagnostic{
-				Range: protocol.Range{
-					Start: protocol.Position{
-						Line:      line,
-						Character: col,
-					},
-					End: protocol.Position{
-						Line:      line,
-						Character: col,
-					},
-				},
-				Severity: protocol.SeverityError,
-				Source:   "LSP: Go compiler",
-				Message:  msg,
-			}
-			if _, ok := wants[pos.Filename]; ok {
-				wants[pos.Filename] = append(wants[pos.Filename], want)
-			} else {
-				t.Errorf("unexpected filename: %v", pos.Filename)
-			}
-		},
-	})
-	if err != nil {
-		t.Fatal(err)
-	}
-	var dirList []string
-	for dir := range dirs {
-		dirList = append(dirList, dir)
-	}
-	exported.Config.Mode = packages.LoadFiles
-	pkgs, err := packages.Load(exported.Config, dirList...)
-	if err != nil {
-		t.Fatal(err)
-	}
-	v := source.NewView()
-	// merge the config objects
-	cfg := *exported.Config
-	cfg.Fset = v.Config.Fset
-	cfg.Mode = packages.LoadSyntax
-	v.Config = &cfg
-	for _, pkg := range pkgs {
-		for _, filename := range pkg.GoFiles {
-			diagnostics, err := diagnostics(v, source.ToURI(filename))
-			if err != nil {
-				t.Fatal(err)
-			}
-			got := diagnostics[filename]
-			sort.Slice(got, func(i int, j int) bool {
-				return got[i].Range.Start.Line < got[j].Range.Start.Line
-			})
-			want := wants[filename]
-			if equal := reflect.DeepEqual(want, got); !equal {
-				t.Errorf("diagnostics failed for %s: (expected: %v), (got: %v)", filename, want, got)
-			}
-		}
-	}
-}
diff --git a/internal/lsp/lsp_test.go b/internal/lsp/lsp_test.go
new file mode 100644
index 0000000..ee1377e
--- /dev/null
+++ b/internal/lsp/lsp_test.go
@@ -0,0 +1,201 @@
+// Copyright 2018 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 lsp
+
+import (
+	"context"
+	"go/token"
+	"io/ioutil"
+	"path/filepath"
+	"reflect"
+	"sort"
+	"strings"
+	"testing"
+
+	"golang.org/x/tools/go/packages"
+	"golang.org/x/tools/go/packages/packagestest"
+	"golang.org/x/tools/internal/lsp/protocol"
+	"golang.org/x/tools/internal/lsp/source"
+)
+
+func TestLSP(t *testing.T) {
+	packagestest.TestAll(t, testLSP)
+}
+
+func testLSP(t *testing.T, exporter packagestest.Exporter) {
+	dir := "testdata"
+	files := packagestest.MustCopyFileTree(dir)
+	subdirs, err := ioutil.ReadDir(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, subdir := range subdirs {
+		if !subdir.IsDir() {
+			continue
+		}
+		dirpath := filepath.Join(dir, subdir.Name())
+		if testFiles, err := ioutil.ReadDir(dirpath); err == nil {
+			for _, file := range testFiles {
+				if trimmed := strings.TrimSuffix(file.Name(), ".in"); trimmed != file.Name() {
+					files[filepath.Join(subdir.Name(), trimmed)] = packagestest.Copy(filepath.Join(dirpath, file.Name()))
+				}
+			}
+		}
+	}
+	modules := []packagestest.Module{
+		{
+			Name:  "golang.org/x/tools/internal/lsp",
+			Files: files,
+		},
+	}
+	exported := packagestest.Export(t, exporter, modules)
+	defer exported.Cleanup()
+
+	dirs := make(map[string]bool)
+
+	// collect results for certain tests
+	expectedDiagnostics := make(map[string][]protocol.Diagnostic)
+	expectedCompletions := make(map[token.Position]*protocol.CompletionItem)
+
+	s := &server{
+		view: source.NewView(),
+	}
+	// merge the config objects
+	cfg := *exported.Config
+	cfg.Fset = s.view.Config.Fset
+	cfg.Mode = packages.LoadSyntax
+	s.view.Config = &cfg
+
+	for _, module := range modules {
+		for fragment := range module.Files {
+			if !strings.HasSuffix(fragment, ".go") {
+				continue
+			}
+			filename := exporter.Filename(exported, module.Name, fragment)
+			expectedDiagnostics[filename] = []protocol.Diagnostic{}
+			dirs[filepath.Dir(filename)] = true
+		}
+	}
+	// Collect any data that needs to be used by subsequent tests.
+	if err := exported.Expect(map[string]interface{}{
+		"diag": func(pos token.Position, msg string) {
+			line := float64(pos.Line - 1)
+			col := float64(pos.Column - 1)
+			want := protocol.Diagnostic{
+				Range: protocol.Range{
+					Start: protocol.Position{
+						Line:      line,
+						Character: col,
+					},
+					End: protocol.Position{
+						Line:      line,
+						Character: col,
+					},
+				},
+				Severity: protocol.SeverityError,
+				Source:   "LSP: Go compiler",
+				Message:  msg,
+			}
+			if _, ok := expectedDiagnostics[pos.Filename]; ok {
+				expectedDiagnostics[pos.Filename] = append(expectedDiagnostics[pos.Filename], want)
+			} else {
+				t.Errorf("unexpected filename: %v", pos.Filename)
+			}
+		},
+		"item": func(pos token.Position, label, detail, kind string) {
+			var k protocol.CompletionItemKind
+			switch kind {
+			case "struct":
+				k = protocol.StructCompletion
+			case "func":
+				k = protocol.FunctionCompletion
+			case "var":
+				k = protocol.VariableCompletion
+			case "type":
+				k = protocol.TypeParameterCompletion
+			case "field":
+				k = protocol.FieldCompletion
+			case "interface":
+				k = protocol.InterfaceCompletion
+			case "const":
+				k = protocol.ConstantCompletion
+			case "method":
+				k = protocol.MethodCompletion
+			}
+			expectedCompletions[pos] = &protocol.CompletionItem{
+				Label:  label,
+				Detail: detail,
+				Kind:   float64(k),
+			}
+		},
+	}); err != nil {
+		t.Fatal(err)
+	}
+
+	// test completion
+	testCompletion(t, exported, s, expectedCompletions)
+
+	// test diagnostics
+	var dirList []string
+	for dir := range dirs {
+		dirList = append(dirList, dir)
+	}
+	exported.Config.Mode = packages.LoadFiles
+	pkgs, err := packages.Load(exported.Config, dirList...)
+	if err != nil {
+		t.Fatal(err)
+	}
+	testDiagnostics(t, s.view, pkgs, expectedDiagnostics)
+}
+
+func testDiagnostics(t *testing.T, v *source.View, pkgs []*packages.Package, wants map[string][]protocol.Diagnostic) {
+	for _, pkg := range pkgs {
+		for _, filename := range pkg.GoFiles {
+			diagnostics, err := diagnostics(v, source.ToURI(filename))
+			if err != nil {
+				t.Fatal(err)
+			}
+			got := diagnostics[filename]
+			sort.Slice(got, func(i int, j int) bool {
+				return got[i].Range.Start.Line < got[j].Range.Start.Line
+			})
+			want := wants[filename]
+			if equal := reflect.DeepEqual(want, got); !equal {
+				t.Errorf("diagnostics failed for %s: (expected: %v), (got: %v)", filepath.Base(filename), want, got)
+			}
+		}
+	}
+}
+
+func testCompletion(t *testing.T, exported *packagestest.Exported, s *server, wants map[token.Position]*protocol.CompletionItem) {
+	if err := exported.Expect(map[string]interface{}{
+		"complete": func(src token.Position, expected []token.Position) {
+			var want []protocol.CompletionItem
+			for _, pos := range expected {
+				want = append(want, *wants[pos])
+			}
+			list, err := s.Completion(context.Background(), &protocol.CompletionParams{
+				TextDocumentPositionParams: protocol.TextDocumentPositionParams{
+					TextDocument: protocol.TextDocumentIdentifier{
+						URI: protocol.DocumentURI(source.ToURI(src.Filename)),
+					},
+					Position: protocol.Position{
+						Line:      float64(src.Line - 1),
+						Character: float64(src.Column - 1),
+					},
+				},
+			})
+			if err != nil {
+				t.Fatal(err)
+			}
+			got := list.Items
+			if equal := reflect.DeepEqual(want, got); !equal {
+				t.Errorf("completion failed for %s:%v:%v: (expected: %v), (got: %v)", filepath.Base(src.Filename), src.Line, src.Column, want, got)
+			}
+		},
+	}); err != nil {
+		t.Fatal(err)
+	}
+}
diff --git a/internal/lsp/source/completion.go b/internal/lsp/source/completion.go
index 5d1e29a..af7131f 100644
--- a/internal/lsp/source/completion.go
+++ b/internal/lsp/source/completion.go
@@ -90,6 +90,9 @@
 			if typ != nil && matchingTypes(typ, obj.Type()) {
 				weight *= 10
 			}
+			if !strings.HasPrefix(obj.Name(), prefix) {
+				return items
+			}
 			item := formatCompletion(obj, pkgStringer, weight, func(v *types.Var) bool {
 				return isParameter(sig, v)
 			})
@@ -203,7 +206,7 @@
 		}
 		scopes = append(scopes, info.Scopes[n])
 	}
-	scopes = append(scopes, pkg.Scope(), types.Universe)
+	scopes = append(scopes, pkg.Scope())
 
 	// Process scopes innermost first.
 	for i, scope := range scopes {
diff --git a/internal/lsp/source/file.go b/internal/lsp/source/file.go
index 1400925..8b9ddb2 100644
--- a/internal/lsp/source/file.go
+++ b/internal/lsp/source/file.go
@@ -8,8 +8,9 @@
 	"fmt"
 	"go/ast"
 	"go/token"
-	"golang.org/x/tools/go/packages"
 	"io/ioutil"
+
+	"golang.org/x/tools/go/packages"
 )
 
 // File holds all the information we know about a file.
diff --git a/internal/lsp/testdata/diagnostics/bad/bad.go b/internal/lsp/testdata/bad/bad.go
similarity index 100%
rename from internal/lsp/testdata/diagnostics/bad/bad.go
rename to internal/lsp/testdata/bad/bad.go
diff --git a/internal/lsp/testdata/diagnostics/bad/bad_util.go b/internal/lsp/testdata/bad/bad_util.go
similarity index 100%
rename from internal/lsp/testdata/diagnostics/bad/bad_util.go
rename to internal/lsp/testdata/bad/bad_util.go
diff --git a/internal/lsp/testdata/diagnostics/bar/bar.go b/internal/lsp/testdata/bar/bar.go
similarity index 100%
rename from internal/lsp/testdata/diagnostics/bar/bar.go
rename to internal/lsp/testdata/bar/bar.go
diff --git a/internal/lsp/testdata/diagnostics/baz/baz.go b/internal/lsp/testdata/baz/baz.go
similarity index 100%
rename from internal/lsp/testdata/diagnostics/baz/baz.go
rename to internal/lsp/testdata/baz/baz.go
diff --git a/internal/lsp/testdata/diagnostics/foo/foo.go b/internal/lsp/testdata/diagnostics/foo/foo.go
deleted file mode 100644
index 18be5d3..0000000
--- a/internal/lsp/testdata/diagnostics/foo/foo.go
+++ /dev/null
@@ -1,3 +0,0 @@
-package foo
-
-func Foo() {}
diff --git a/internal/lsp/testdata/foo/foo.go b/internal/lsp/testdata/foo/foo.go
new file mode 100644
index 0000000..bb92eb1
--- /dev/null
+++ b/internal/lsp/testdata/foo/foo.go
@@ -0,0 +1,23 @@
+package foo
+
+type StructFoo struct { //@mark(StructFoo, "StructFoo"),item(StructFoo, "StructFoo", "struct{...}", "struct")
+	Value int //@mark(Value, "Value"),item(Value, "Value", "int", "field")
+}
+
+// TODO(rstambler): Create pre-set builtins?
+//@mark(Error, ""),item(Error, "Error()", "string", "method")
+
+func Foo() { //@mark(Foo, "Foo"),item(Foo, "Foo()", "", "func")
+	var err error
+	err.Error() //@complete("E", Error)
+}
+
+func _() {
+	var sFoo StructFoo           //@complete("t", StructFoo)
+	if x := sFoo; x.Value == 1 { //@complete("V", Value)
+		return
+	}
+}
+
+//@complete("", Foo, IntFoo, StructFoo)
+type IntFoo int //@mark(IntFoo, "IntFoo"),item(IntFoo, "IntFoo", "int", "type")
diff --git a/internal/lsp/testdata/diagnostics/good/good.go b/internal/lsp/testdata/good/good.go
similarity index 100%
rename from internal/lsp/testdata/diagnostics/good/good.go
rename to internal/lsp/testdata/good/good.go
diff --git a/internal/lsp/testdata/diagnostics/good/good_util.go b/internal/lsp/testdata/good/good_util.go
similarity index 100%
rename from internal/lsp/testdata/diagnostics/good/good_util.go
rename to internal/lsp/testdata/good/good_util.go
diff --git a/internal/lsp/testdata/diagnostics/noparse/noparse.go.in b/internal/lsp/testdata/noparse/noparse.go.in
similarity index 100%
rename from internal/lsp/testdata/diagnostics/noparse/noparse.go.in
rename to internal/lsp/testdata/noparse/noparse.go.in