// 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.

// Package tests exports functionality to be used across a variety of gopls tests.
package tests

import (
	"bytes"
	"context"
	"flag"
	"fmt"
	"go/ast"
	"go/token"
	"io/ioutil"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"sync"
	"testing"
	"time"

	"golang.org/x/tools/go/expect"
	"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"
	"golang.org/x/tools/internal/span"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/txtar"
)

const (
	overlayFileSuffix = ".overlay"
	goldenFileSuffix  = ".golden"
	inFileSuffix      = ".in"
	summaryFile       = "summary.txt"
	testModule        = "golang.org/x/tools/internal/lsp"
)

var UpdateGolden = flag.Bool("golden", false, "Update golden files")

type CodeLens map[span.URI][]protocol.CodeLens
type Diagnostics map[span.URI][]*source.Diagnostic
type CompletionItems map[token.Pos]*source.CompletionItem
type Completions map[span.Span][]Completion
type CompletionSnippets map[span.Span][]CompletionSnippet
type UnimportedCompletions map[span.Span][]Completion
type DeepCompletions map[span.Span][]Completion
type FuzzyCompletions map[span.Span][]Completion
type CaseSensitiveCompletions map[span.Span][]Completion
type RankCompletions map[span.Span][]Completion
type FoldingRanges []span.Span
type Formats []span.Span
type Imports []span.Span
type SuggestedFixes map[span.Span][]string
type FunctionExtractions map[span.Span]span.Span
type Definitions map[span.Span]Definition
type Implementations map[span.Span][]span.Span
type Highlights map[span.Span][]span.Span
type References map[span.Span][]span.Span
type Renames map[span.Span]string
type PrepareRenames map[span.Span]*source.PrepareItem
type Symbols map[span.URI][]protocol.DocumentSymbol
type SymbolsChildren map[string][]protocol.DocumentSymbol
type SymbolInformation map[span.Span]protocol.SymbolInformation
type WorkspaceSymbols map[string][]protocol.SymbolInformation
type Signatures map[span.Span]*protocol.SignatureHelp
type Links map[span.URI][]Link

type Data struct {
	Config                        packages.Config
	Exported                      *packagestest.Exported
	CodeLens                      CodeLens
	Diagnostics                   Diagnostics
	CompletionItems               CompletionItems
	Completions                   Completions
	CompletionSnippets            CompletionSnippets
	UnimportedCompletions         UnimportedCompletions
	DeepCompletions               DeepCompletions
	FuzzyCompletions              FuzzyCompletions
	CaseSensitiveCompletions      CaseSensitiveCompletions
	RankCompletions               RankCompletions
	FoldingRanges                 FoldingRanges
	Formats                       Formats
	Imports                       Imports
	SuggestedFixes                SuggestedFixes
	FunctionExtractions           FunctionExtractions
	Definitions                   Definitions
	Implementations               Implementations
	Highlights                    Highlights
	References                    References
	Renames                       Renames
	PrepareRenames                PrepareRenames
	Symbols                       Symbols
	symbolsChildren               SymbolsChildren
	symbolInformation             SymbolInformation
	WorkspaceSymbols              WorkspaceSymbols
	FuzzyWorkspaceSymbols         WorkspaceSymbols
	CaseSensitiveWorkspaceSymbols WorkspaceSymbols
	Signatures                    Signatures
	Links                         Links

	t         testing.TB
	fragments map[string]string
	dir       string
	Folder    string
	golden    map[string]*Golden

	ModfileFlagAvailable bool

	mappersMu sync.Mutex
	mappers   map[span.URI]*protocol.ColumnMapper
}

type Tests interface {
	CodeLens(*testing.T, span.URI, []protocol.CodeLens)
	Diagnostics(*testing.T, span.URI, []*source.Diagnostic)
	Completion(*testing.T, span.Span, Completion, CompletionItems)
	CompletionSnippet(*testing.T, span.Span, CompletionSnippet, bool, CompletionItems)
	UnimportedCompletion(*testing.T, span.Span, Completion, CompletionItems)
	DeepCompletion(*testing.T, span.Span, Completion, CompletionItems)
	FuzzyCompletion(*testing.T, span.Span, Completion, CompletionItems)
	CaseSensitiveCompletion(*testing.T, span.Span, Completion, CompletionItems)
	RankCompletion(*testing.T, span.Span, Completion, CompletionItems)
	FoldingRanges(*testing.T, span.Span)
	Format(*testing.T, span.Span)
	Import(*testing.T, span.Span)
	SuggestedFix(*testing.T, span.Span, []string)
	FunctionExtraction(*testing.T, span.Span, span.Span)
	Definition(*testing.T, span.Span, Definition)
	Implementation(*testing.T, span.Span, []span.Span)
	Highlight(*testing.T, span.Span, []span.Span)
	References(*testing.T, span.Span, []span.Span)
	Rename(*testing.T, span.Span, string)
	PrepareRename(*testing.T, span.Span, *source.PrepareItem)
	Symbols(*testing.T, span.URI, []protocol.DocumentSymbol)
	WorkspaceSymbols(*testing.T, string, []protocol.SymbolInformation, map[string]struct{})
	FuzzyWorkspaceSymbols(*testing.T, string, []protocol.SymbolInformation, map[string]struct{})
	CaseSensitiveWorkspaceSymbols(*testing.T, string, []protocol.SymbolInformation, map[string]struct{})
	SignatureHelp(*testing.T, span.Span, *protocol.SignatureHelp)
	Link(*testing.T, span.URI, []Link)
}

type Definition struct {
	Name      string
	IsType    bool
	OnlyHover bool
	Src, Def  span.Span
}

type CompletionTestType int

const (
	// Default runs the standard completion tests.
	CompletionDefault = CompletionTestType(iota)

	// Unimported tests the autocompletion of unimported packages.
	CompletionUnimported

	// Deep tests deep completion.
	CompletionDeep

	// Fuzzy tests deep completion and fuzzy matching.
	CompletionFuzzy

	// CaseSensitive tests case sensitive completion.
	CompletionCaseSensitive

	// CompletionRank candidates in test must be valid and in the right relative order.
	CompletionRank
)

type WorkspaceSymbolsTestType int

const (
	// Default runs the standard workspace symbols tests.
	WorkspaceSymbolsDefault = WorkspaceSymbolsTestType(iota)

	// Fuzzy tests workspace symbols with fuzzy matching.
	WorkspaceSymbolsFuzzy

	// CaseSensitive tests workspace symbols with case sensitive.
	WorkspaceSymbolsCaseSensitive
)

type Completion struct {
	CompletionItems []token.Pos
}

type CompletionSnippet struct {
	CompletionItem     token.Pos
	PlainSnippet       string
	PlaceholderSnippet string
}

type Link struct {
	Src          span.Span
	Target       string
	NotePosition token.Position
}

type Golden struct {
	Filename string
	Archive  *txtar.Archive
	Modified bool
}

func Context(t testing.TB) context.Context {
	return context.Background()
}

func DefaultOptions() source.Options {
	o := source.DefaultOptions()
	o.SupportedCodeActions = map[source.FileKind]map[protocol.CodeActionKind]bool{
		source.Go: {
			protocol.SourceOrganizeImports: true,
			protocol.QuickFix:              true,
			protocol.RefactorRewrite:       true,
			protocol.RefactorExtract:       true,
			protocol.SourceFixAll:          true,
		},
		source.Mod: {
			protocol.SourceOrganizeImports: true,
		},
		source.Sum: {},
	}
	o.UserOptions.EnabledCodeLens[source.CommandTest.Name] = true
	o.HoverKind = source.SynopsisDocumentation
	o.InsertTextFormat = protocol.SnippetTextFormat
	o.CompletionBudget = time.Minute
	o.HierarchicalDocumentSymbolSupport = true
	return o
}

var (
	go115 = false
)

// Load creates the folder structure required when testing with modules.
// The directory structure of a test needs to look like the example below:
//
// - dir
// 	 - primarymod
// 		 - .go files
// 		 - packages
// 		 - go.mod (optional)
// 	 - modules
//		 - repoa
//			 - mod1
//				 - .go files
//				 -  packages
//				 - go.mod (optional)
//			 - mod2
//		 - repob
//			 - mod1
//
// All the files that are primarily being tested should be in the primarymod folder,
// any auxillary packages should be declared in the modules folder.
// The modules folder requires each module to have the following format: repo/module
// Then inside each repo/module, there can be any number of packages and files that are
// needed to test the primarymod.
func Load(t testing.TB, exporter packagestest.Exporter, dir string) []*Data {
	t.Helper()

	folders, err := testFolders(dir)
	if err != nil {
		t.Fatalf("could not get test folders for %v, %v", dir, err)
	}

	var data []*Data
	for _, folder := range folders {
		datum := &Data{
			CodeLens:                      make(CodeLens),
			Diagnostics:                   make(Diagnostics),
			CompletionItems:               make(CompletionItems),
			Completions:                   make(Completions),
			CompletionSnippets:            make(CompletionSnippets),
			UnimportedCompletions:         make(UnimportedCompletions),
			DeepCompletions:               make(DeepCompletions),
			FuzzyCompletions:              make(FuzzyCompletions),
			RankCompletions:               make(RankCompletions),
			CaseSensitiveCompletions:      make(CaseSensitiveCompletions),
			Definitions:                   make(Definitions),
			Implementations:               make(Implementations),
			Highlights:                    make(Highlights),
			References:                    make(References),
			Renames:                       make(Renames),
			PrepareRenames:                make(PrepareRenames),
			SuggestedFixes:                make(SuggestedFixes),
			FunctionExtractions:           make(FunctionExtractions),
			Symbols:                       make(Symbols),
			symbolsChildren:               make(SymbolsChildren),
			symbolInformation:             make(SymbolInformation),
			WorkspaceSymbols:              make(WorkspaceSymbols),
			FuzzyWorkspaceSymbols:         make(WorkspaceSymbols),
			CaseSensitiveWorkspaceSymbols: make(WorkspaceSymbols),
			Signatures:                    make(Signatures),
			Links:                         make(Links),

			t:         t,
			dir:       folder,
			Folder:    folder,
			fragments: map[string]string{},
			golden:    map[string]*Golden{},
			mappers:   map[span.URI]*protocol.ColumnMapper{},
		}

		if !*UpdateGolden {
			summary := filepath.Join(filepath.FromSlash(folder), summaryFile+goldenFileSuffix)
			if _, err := os.Stat(summary); os.IsNotExist(err) {
				t.Fatalf("could not find golden file summary.txt in %#v", folder)
			}
			archive, err := txtar.ParseFile(summary)
			if err != nil {
				t.Fatalf("could not read golden file %v/%v: %v", folder, summary, err)
			}
			datum.golden[summaryFile] = &Golden{
				Filename: summary,
				Archive:  archive,
			}
		}

		modules, _ := packagestest.GroupFilesByModules(folder)
		for i, m := range modules {
			for fragment, operation := range m.Files {
				if trimmed := strings.TrimSuffix(fragment, goldenFileSuffix); trimmed != fragment {
					delete(m.Files, fragment)
					goldFile := filepath.Join(m.Name, fragment)
					if i == 0 {
						goldFile = filepath.Join(m.Name, "primarymod", fragment)
					}
					archive, err := txtar.ParseFile(goldFile)
					if err != nil {
						t.Fatalf("could not read golden file %v: %v", fragment, err)
					}
					datum.golden[trimmed] = &Golden{
						Filename: goldFile,
						Archive:  archive,
					}
				} else if trimmed := strings.TrimSuffix(fragment, inFileSuffix); trimmed != fragment {
					delete(m.Files, fragment)
					m.Files[trimmed] = operation
				} else if index := strings.Index(fragment, overlayFileSuffix); index >= 0 {
					delete(m.Files, fragment)
					partial := fragment[:index] + fragment[index+len(overlayFileSuffix):]
					overlayFile := filepath.Join(m.Name, fragment)
					if i == 0 {
						overlayFile = filepath.Join(m.Name, "primarymod", fragment)
					}
					contents, err := ioutil.ReadFile(overlayFile)
					if err != nil {
						t.Fatal(err)
					}
					m.Overlay[partial] = contents
				}
			}
		}
		if len(modules) > 0 {
			// For certain LSP related tests to run, make sure that the primary
			// module for the passed in directory is testModule.
			modules[0].Name = testModule
		}
		// Add exampleModule to provide tests with another pkg.
		datum.Exported = packagestest.Export(t, exporter, modules)
		for _, m := range modules {
			for fragment := range m.Files {
				filename := datum.Exported.File(m.Name, fragment)
				datum.fragments[filename] = fragment
			}
		}

		// Turn off go/packages debug logging.
		datum.Exported.Config.Logf = nil
		datum.Config.Logf = nil

		// Merge the exported.Config with the view.Config.
		datum.Config = *datum.Exported.Config
		datum.Config.Fset = token.NewFileSet()
		datum.Config.Context = Context(nil)
		datum.Config.ParseFile = func(fset *token.FileSet, filename string, src []byte) (*ast.File, error) {
			panic("ParseFile should not be called")
		}

		// Do a first pass to collect special markers for completion and workspace symbols.
		if err := datum.Exported.Expect(map[string]interface{}{
			"item": func(name string, r packagestest.Range, _ []string) {
				datum.Exported.Mark(name, r)
			},
			"symbol": func(name string, r packagestest.Range, _ []string) {
				datum.Exported.Mark(name, r)
			},
		}); err != nil {
			t.Fatal(err)
		}

		// Collect any data that needs to be used by subsequent tests.
		if err := datum.Exported.Expect(map[string]interface{}{
			"codelens":        datum.collectCodeLens,
			"diag":            datum.collectDiagnostics,
			"item":            datum.collectCompletionItems,
			"complete":        datum.collectCompletions(CompletionDefault),
			"unimported":      datum.collectCompletions(CompletionUnimported),
			"deep":            datum.collectCompletions(CompletionDeep),
			"fuzzy":           datum.collectCompletions(CompletionFuzzy),
			"casesensitive":   datum.collectCompletions(CompletionCaseSensitive),
			"rank":            datum.collectCompletions(CompletionRank),
			"snippet":         datum.collectCompletionSnippets,
			"fold":            datum.collectFoldingRanges,
			"format":          datum.collectFormats,
			"import":          datum.collectImports,
			"godef":           datum.collectDefinitions,
			"implementations": datum.collectImplementations,
			"typdef":          datum.collectTypeDefinitions,
			"hover":           datum.collectHoverDefinitions,
			"highlight":       datum.collectHighlights,
			"refs":            datum.collectReferences,
			"rename":          datum.collectRenames,
			"prepare":         datum.collectPrepareRenames,
			"symbol":          datum.collectSymbols,
			"signature":       datum.collectSignatures,
			"link":            datum.collectLinks,
			"suggestedfix":    datum.collectSuggestedFixes,
			"extractfunc":     datum.collectFunctionExtractions,
		}); err != nil {
			t.Fatal(err)
		}
		for _, symbols := range datum.Symbols {
			for i := range symbols {
				children := datum.symbolsChildren[symbols[i].Name]
				symbols[i].Children = children
			}
		}
		// Collect names for the entries that require golden files.
		if err := datum.Exported.Expect(map[string]interface{}{
			"godef":                        datum.collectDefinitionNames,
			"hover":                        datum.collectDefinitionNames,
			"workspacesymbol":              datum.collectWorkspaceSymbols(WorkspaceSymbolsDefault),
			"workspacesymbolfuzzy":         datum.collectWorkspaceSymbols(WorkspaceSymbolsFuzzy),
			"workspacesymbolcasesensitive": datum.collectWorkspaceSymbols(WorkspaceSymbolsCaseSensitive),
		}); err != nil {
			t.Fatal(err)
		}
		data = append(data, datum)
	}
	return data
}

func Run(t *testing.T, tests Tests, data *Data) {
	t.Helper()
	checkData(t, data)

	eachCompletion := func(t *testing.T, cases map[span.Span][]Completion, test func(*testing.T, span.Span, Completion, CompletionItems)) {
		t.Helper()

		for src, exp := range cases {
			for i, e := range exp {
				t.Run(SpanName(src)+"_"+strconv.Itoa(i), func(t *testing.T) {
					t.Helper()
					if strings.Contains(t.Name(), "cgo") {
						testenv.NeedsTool(t, "cgo")
					}
					if !go115 && strings.Contains(t.Name(), "declarecgo") {
						t.Skip("test requires Go 1.15")
					}
					test(t, src, e, data.CompletionItems)
				})
			}

		}
	}

	eachWorkspaceSymbols := func(t *testing.T, cases map[string][]protocol.SymbolInformation, test func(*testing.T, string, []protocol.SymbolInformation, map[string]struct{})) {
		t.Helper()

		for query, expectedSymbols := range cases {
			name := query
			if name == "" {
				name = "EmptyQuery"
			}
			t.Run(name, func(t *testing.T) {
				t.Helper()
				dirs := make(map[string]struct{})
				for _, si := range expectedSymbols {
					d := filepath.Dir(si.Location.URI.SpanURI().Filename())
					if _, ok := dirs[d]; !ok {
						dirs[d] = struct{}{}
					}
				}
				test(t, query, expectedSymbols, dirs)
			})
		}
	}

	t.Run("Completion", func(t *testing.T) {
		t.Helper()
		eachCompletion(t, data.Completions, tests.Completion)
	})

	t.Run("CompletionSnippets", func(t *testing.T) {
		t.Helper()
		for _, placeholders := range []bool{true, false} {
			for src, expecteds := range data.CompletionSnippets {
				for i, expected := range expecteds {
					name := SpanName(src) + "_" + strconv.Itoa(i+1)
					if placeholders {
						name += "_placeholders"
					}

					t.Run(name, func(t *testing.T) {
						t.Helper()
						tests.CompletionSnippet(t, src, expected, placeholders, data.CompletionItems)
					})
				}
			}
		}
	})

	t.Run("UnimportedCompletion", func(t *testing.T) {
		t.Helper()
		eachCompletion(t, data.UnimportedCompletions, tests.UnimportedCompletion)
	})

	t.Run("DeepCompletion", func(t *testing.T) {
		t.Helper()
		eachCompletion(t, data.DeepCompletions, tests.DeepCompletion)
	})

	t.Run("FuzzyCompletion", func(t *testing.T) {
		t.Helper()
		eachCompletion(t, data.FuzzyCompletions, tests.FuzzyCompletion)
	})

	t.Run("CaseSensitiveCompletion", func(t *testing.T) {
		t.Helper()
		eachCompletion(t, data.CaseSensitiveCompletions, tests.CaseSensitiveCompletion)
	})

	t.Run("RankCompletions", func(t *testing.T) {
		t.Helper()
		eachCompletion(t, data.RankCompletions, tests.RankCompletion)
	})

	t.Run("CodeLens", func(t *testing.T) {
		t.Helper()
		for uri, want := range data.CodeLens {
			// Check if we should skip this URI if the -modfile flag is not available.
			if shouldSkip(data, uri) {
				continue
			}
			t.Run(uriName(uri), func(t *testing.T) {
				t.Helper()
				tests.CodeLens(t, uri, want)
			})
		}
	})

	t.Run("Diagnostics", func(t *testing.T) {
		t.Helper()
		for uri, want := range data.Diagnostics {
			// Check if we should skip this URI if the -modfile flag is not available.
			if shouldSkip(data, uri) {
				continue
			}
			t.Run(uriName(uri), func(t *testing.T) {
				t.Helper()
				tests.Diagnostics(t, uri, want)
			})
		}
	})

	t.Run("FoldingRange", func(t *testing.T) {
		t.Helper()
		for _, spn := range data.FoldingRanges {
			t.Run(uriName(spn.URI()), func(t *testing.T) {
				t.Helper()
				tests.FoldingRanges(t, spn)
			})
		}
	})

	t.Run("Format", func(t *testing.T) {
		t.Helper()
		for _, spn := range data.Formats {
			t.Run(uriName(spn.URI()), func(t *testing.T) {
				t.Helper()
				tests.Format(t, spn)
			})
		}
	})

	t.Run("Import", func(t *testing.T) {
		t.Helper()
		for _, spn := range data.Imports {
			t.Run(uriName(spn.URI()), func(t *testing.T) {
				t.Helper()
				tests.Import(t, spn)
			})
		}
	})

	t.Run("SuggestedFix", func(t *testing.T) {
		t.Helper()
		for spn, actionKinds := range data.SuggestedFixes {
			// Check if we should skip this spn if the -modfile flag is not available.
			if shouldSkip(data, spn.URI()) {
				continue
			}
			t.Run(SpanName(spn), func(t *testing.T) {
				t.Helper()
				tests.SuggestedFix(t, spn, actionKinds)
			})
		}
	})

	t.Run("FunctionExtraction", func(t *testing.T) {
		t.Helper()
		for start, end := range data.FunctionExtractions {
			// Check if we should skip this spn if the -modfile flag is not available.
			if shouldSkip(data, start.URI()) {
				continue
			}
			t.Run(SpanName(start), func(t *testing.T) {
				t.Helper()
				tests.FunctionExtraction(t, start, end)
			})
		}
	})

	t.Run("Definition", func(t *testing.T) {
		t.Helper()
		for spn, d := range data.Definitions {
			t.Run(SpanName(spn), func(t *testing.T) {
				t.Helper()
				if strings.Contains(t.Name(), "cgo") {
					testenv.NeedsTool(t, "cgo")
				}
				if !go115 && strings.Contains(t.Name(), "declarecgo") {
					t.Skip("test requires Go 1.15")
				}
				tests.Definition(t, spn, d)
			})
		}
	})

	t.Run("Implementation", func(t *testing.T) {
		t.Helper()
		for spn, m := range data.Implementations {
			t.Run(SpanName(spn), func(t *testing.T) {
				t.Helper()
				tests.Implementation(t, spn, m)
			})
		}
	})

	t.Run("Highlight", func(t *testing.T) {
		t.Helper()
		for pos, locations := range data.Highlights {
			t.Run(SpanName(pos), func(t *testing.T) {
				t.Helper()
				tests.Highlight(t, pos, locations)
			})
		}
	})

	t.Run("References", func(t *testing.T) {
		t.Helper()
		for src, itemList := range data.References {
			t.Run(SpanName(src), func(t *testing.T) {
				t.Helper()
				tests.References(t, src, itemList)
			})
		}
	})

	t.Run("Renames", func(t *testing.T) {
		t.Helper()
		for spn, newText := range data.Renames {
			t.Run(uriName(spn.URI())+"_"+newText, func(t *testing.T) {
				t.Helper()
				tests.Rename(t, spn, newText)
			})
		}
	})

	t.Run("PrepareRenames", func(t *testing.T) {
		t.Helper()
		for src, want := range data.PrepareRenames {
			t.Run(SpanName(src), func(t *testing.T) {
				t.Helper()
				tests.PrepareRename(t, src, want)
			})
		}
	})

	t.Run("Symbols", func(t *testing.T) {
		t.Helper()
		for uri, expectedSymbols := range data.Symbols {
			t.Run(uriName(uri), func(t *testing.T) {
				t.Helper()
				tests.Symbols(t, uri, expectedSymbols)
			})
		}
	})

	t.Run("WorkspaceSymbols", func(t *testing.T) {
		t.Helper()
		eachWorkspaceSymbols(t, data.WorkspaceSymbols, tests.WorkspaceSymbols)
	})

	t.Run("FuzzyWorkspaceSymbols", func(t *testing.T) {
		t.Helper()
		eachWorkspaceSymbols(t, data.FuzzyWorkspaceSymbols, tests.FuzzyWorkspaceSymbols)
	})

	t.Run("CaseSensitiveWorkspaceSymbols", func(t *testing.T) {
		t.Helper()
		eachWorkspaceSymbols(t, data.CaseSensitiveWorkspaceSymbols, tests.CaseSensitiveWorkspaceSymbols)
	})

	t.Run("SignatureHelp", func(t *testing.T) {
		t.Helper()
		for spn, expectedSignature := range data.Signatures {
			t.Run(SpanName(spn), func(t *testing.T) {
				t.Helper()
				tests.SignatureHelp(t, spn, expectedSignature)
			})
		}
	})

	t.Run("Link", func(t *testing.T) {
		t.Helper()
		for uri, wantLinks := range data.Links {
			// If we are testing GOPATH, then we do not want links with
			// the versions attached (pkg.go.dev/repoa/moda@v1.1.0/pkg),
			// unless the file is a go.mod, then we can skip it alltogether.
			if data.Exported.Exporter == packagestest.GOPATH {
				if strings.HasSuffix(uri.Filename(), ".mod") {
					continue
				}
				re := regexp.MustCompile(`@v\d+\.\d+\.[\w-]+`)
				for i, link := range wantLinks {
					wantLinks[i].Target = re.ReplaceAllString(link.Target, "")
				}
			}
			t.Run(uriName(uri), func(t *testing.T) {
				t.Helper()
				tests.Link(t, uri, wantLinks)
			})
		}
	})

	if *UpdateGolden {
		for _, golden := range data.golden {
			if !golden.Modified {
				continue
			}
			sort.Slice(golden.Archive.Files, func(i, j int) bool {
				return golden.Archive.Files[i].Name < golden.Archive.Files[j].Name
			})
			if err := ioutil.WriteFile(golden.Filename, txtar.Format(golden.Archive), 0666); err != nil {
				t.Fatal(err)
			}
		}
	}
}

func checkData(t *testing.T, data *Data) {
	buf := &bytes.Buffer{}
	diagnosticsCount := 0
	for _, want := range data.Diagnostics {
		diagnosticsCount += len(want)
	}
	linksCount := 0
	for _, want := range data.Links {
		linksCount += len(want)
	}
	definitionCount := 0
	typeDefinitionCount := 0
	for _, d := range data.Definitions {
		if d.IsType {
			typeDefinitionCount++
		} else {
			definitionCount++
		}
	}

	snippetCount := 0
	for _, want := range data.CompletionSnippets {
		snippetCount += len(want)
	}

	countCompletions := func(c map[span.Span][]Completion) (count int) {
		for _, want := range c {
			count += len(want)
		}
		return count
	}

	countCodeLens := func(c map[span.URI][]protocol.CodeLens) (count int) {
		for _, want := range c {
			count += len(want)
		}
		return count
	}

	fmt.Fprintf(buf, "CodeLensCount = %v\n", countCodeLens(data.CodeLens))
	fmt.Fprintf(buf, "CompletionsCount = %v\n", countCompletions(data.Completions))
	fmt.Fprintf(buf, "CompletionSnippetCount = %v\n", snippetCount)
	fmt.Fprintf(buf, "UnimportedCompletionsCount = %v\n", countCompletions(data.UnimportedCompletions))
	fmt.Fprintf(buf, "DeepCompletionsCount = %v\n", countCompletions(data.DeepCompletions))
	fmt.Fprintf(buf, "FuzzyCompletionsCount = %v\n", countCompletions(data.FuzzyCompletions))
	fmt.Fprintf(buf, "RankedCompletionsCount = %v\n", countCompletions(data.RankCompletions))
	fmt.Fprintf(buf, "CaseSensitiveCompletionsCount = %v\n", countCompletions(data.CaseSensitiveCompletions))
	fmt.Fprintf(buf, "DiagnosticsCount = %v\n", diagnosticsCount)
	fmt.Fprintf(buf, "FoldingRangesCount = %v\n", len(data.FoldingRanges))
	fmt.Fprintf(buf, "FormatCount = %v\n", len(data.Formats))
	fmt.Fprintf(buf, "ImportCount = %v\n", len(data.Imports))
	fmt.Fprintf(buf, "SuggestedFixCount = %v\n", len(data.SuggestedFixes))
	fmt.Fprintf(buf, "FunctionExtractionCount = %v\n", len(data.FunctionExtractions))
	fmt.Fprintf(buf, "DefinitionsCount = %v\n", definitionCount)
	fmt.Fprintf(buf, "TypeDefinitionsCount = %v\n", typeDefinitionCount)
	fmt.Fprintf(buf, "HighlightsCount = %v\n", len(data.Highlights))
	fmt.Fprintf(buf, "ReferencesCount = %v\n", len(data.References))
	fmt.Fprintf(buf, "RenamesCount = %v\n", len(data.Renames))
	fmt.Fprintf(buf, "PrepareRenamesCount = %v\n", len(data.PrepareRenames))
	fmt.Fprintf(buf, "SymbolsCount = %v\n", len(data.Symbols))
	fmt.Fprintf(buf, "WorkspaceSymbolsCount = %v\n", len(data.WorkspaceSymbols))
	fmt.Fprintf(buf, "FuzzyWorkspaceSymbolsCount = %v\n", len(data.FuzzyWorkspaceSymbols))
	fmt.Fprintf(buf, "CaseSensitiveWorkspaceSymbolsCount = %v\n", len(data.CaseSensitiveWorkspaceSymbols))
	fmt.Fprintf(buf, "SignaturesCount = %v\n", len(data.Signatures))
	fmt.Fprintf(buf, "LinksCount = %v\n", linksCount)
	fmt.Fprintf(buf, "ImplementationsCount = %v\n", len(data.Implementations))

	want := string(data.Golden("summary", summaryFile, func() ([]byte, error) {
		return buf.Bytes(), nil
	}))
	got := buf.String()
	if want != got {
		t.Errorf("test summary does not match:\n%s", Diff(want, got))
	}
}

func (data *Data) Mapper(uri span.URI) (*protocol.ColumnMapper, error) {
	data.mappersMu.Lock()
	defer data.mappersMu.Unlock()

	if _, ok := data.mappers[uri]; !ok {
		content, err := data.Exported.FileContents(uri.Filename())
		if err != nil {
			return nil, err
		}
		converter := span.NewContentConverter(uri.Filename(), content)
		data.mappers[uri] = &protocol.ColumnMapper{
			URI:       uri,
			Converter: converter,
			Content:   content,
		}
	}
	return data.mappers[uri], nil
}

func (data *Data) Golden(tag string, target string, update func() ([]byte, error)) []byte {
	data.t.Helper()
	fragment, found := data.fragments[target]
	if !found {
		if filepath.IsAbs(target) {
			data.t.Fatalf("invalid golden file fragment %v", target)
		}
		fragment = target
	}
	golden := data.golden[fragment]
	if golden == nil {
		if !*UpdateGolden {
			data.t.Fatalf("could not find golden file %v: %v", fragment, tag)
		}
		var subdir string
		if fragment != summaryFile {
			subdir = "primarymod"
		}
		golden = &Golden{
			Filename: filepath.Join(data.dir, subdir, fragment+goldenFileSuffix),
			Archive:  &txtar.Archive{},
			Modified: true,
		}
		data.golden[fragment] = golden
	}
	var file *txtar.File
	for i := range golden.Archive.Files {
		f := &golden.Archive.Files[i]
		if f.Name == tag {
			file = f
			break
		}
	}
	if *UpdateGolden {
		if file == nil {
			golden.Archive.Files = append(golden.Archive.Files, txtar.File{
				Name: tag,
			})
			file = &golden.Archive.Files[len(golden.Archive.Files)-1]
		}
		contents, err := update()
		if err != nil {
			data.t.Fatalf("could not update golden file %v: %v", fragment, err)
		}
		file.Data = append(contents, '\n') // add trailing \n for txtar
		golden.Modified = true

	}
	if file == nil {
		data.t.Fatalf("could not find golden contents %v: %v", fragment, tag)
	}
	return file.Data[:len(file.Data)-1] // drop the trailing \n
}

func (data *Data) collectCodeLens(spn span.Span, title, cmd string) {
	if _, ok := data.CodeLens[spn.URI()]; !ok {
		data.CodeLens[spn.URI()] = []protocol.CodeLens{}
	}
	m, err := data.Mapper(spn.URI())
	if err != nil {
		return
	}
	rng, err := m.Range(spn)
	if err != nil {
		return
	}
	data.CodeLens[spn.URI()] = append(data.CodeLens[spn.URI()], protocol.CodeLens{
		Range: rng,
		Command: protocol.Command{
			Title:   title,
			Command: cmd,
		},
	})
}

func (data *Data) collectDiagnostics(spn span.Span, msgSource, msg, msgSeverity string) {
	if _, ok := data.Diagnostics[spn.URI()]; !ok {
		data.Diagnostics[spn.URI()] = []*source.Diagnostic{}
	}
	m, err := data.Mapper(spn.URI())
	if err != nil {
		return
	}
	rng, err := m.Range(spn)
	if err != nil {
		return
	}
	severity := protocol.SeverityError
	switch msgSeverity {
	case "error":
		severity = protocol.SeverityError
	case "warning":
		severity = protocol.SeverityWarning
	case "hint":
		severity = protocol.SeverityHint
	case "information":
		severity = protocol.SeverityInformation
	}
	// This is not the correct way to do this, but it seems excessive to do the full conversion here.
	want := &source.Diagnostic{
		Range:    rng,
		Severity: severity,
		Source:   msgSource,
		Message:  msg,
	}
	data.Diagnostics[spn.URI()] = append(data.Diagnostics[spn.URI()], want)
}

func (data *Data) collectCompletions(typ CompletionTestType) func(span.Span, []token.Pos) {
	result := func(m map[span.Span][]Completion, src span.Span, expected []token.Pos) {
		m[src] = append(m[src], Completion{
			CompletionItems: expected,
		})
	}
	switch typ {
	case CompletionDeep:
		return func(src span.Span, expected []token.Pos) {
			result(data.DeepCompletions, src, expected)
		}
	case CompletionUnimported:
		return func(src span.Span, expected []token.Pos) {
			result(data.UnimportedCompletions, src, expected)
		}
	case CompletionFuzzy:
		return func(src span.Span, expected []token.Pos) {
			result(data.FuzzyCompletions, src, expected)
		}
	case CompletionRank:
		return func(src span.Span, expected []token.Pos) {
			result(data.RankCompletions, src, expected)
		}
	case CompletionCaseSensitive:
		return func(src span.Span, expected []token.Pos) {
			result(data.CaseSensitiveCompletions, src, expected)
		}
	default:
		return func(src span.Span, expected []token.Pos) {
			result(data.Completions, src, expected)
		}
	}
}

func (data *Data) collectCompletionItems(pos token.Pos, args []string) {
	if len(args) < 3 {
		loc := data.Exported.ExpectFileSet.Position(pos)
		data.t.Fatalf("%s:%d: @item expects at least 3 args, got %d",
			loc.Filename, loc.Line, len(args))
	}
	label, detail, kind := args[0], args[1], args[2]
	var documentation string
	if len(args) == 4 {
		documentation = args[3]
	}
	data.CompletionItems[pos] = &source.CompletionItem{
		Label:         label,
		Detail:        detail,
		Kind:          protocol.ParseCompletionItemKind(kind),
		Documentation: documentation,
	}
}

func (data *Data) collectFoldingRanges(spn span.Span) {
	data.FoldingRanges = append(data.FoldingRanges, spn)
}

func (data *Data) collectFormats(spn span.Span) {
	data.Formats = append(data.Formats, spn)
}

func (data *Data) collectImports(spn span.Span) {
	data.Imports = append(data.Imports, spn)
}

func (data *Data) collectSuggestedFixes(spn span.Span, actionKind string) {
	if _, ok := data.SuggestedFixes[spn]; !ok {
		data.SuggestedFixes[spn] = []string{}
	}
	data.SuggestedFixes[spn] = append(data.SuggestedFixes[spn], actionKind)
}

func (data *Data) collectFunctionExtractions(start span.Span, end span.Span) {
	if _, ok := data.FunctionExtractions[start]; !ok {
		data.FunctionExtractions[start] = end
	}
}

func (data *Data) collectDefinitions(src, target span.Span) {
	data.Definitions[src] = Definition{
		Src: src,
		Def: target,
	}
}

func (data *Data) collectImplementations(src span.Span, targets []span.Span) {
	data.Implementations[src] = targets
}

func (data *Data) collectHoverDefinitions(src, target span.Span) {
	data.Definitions[src] = Definition{
		Src:       src,
		Def:       target,
		OnlyHover: true,
	}
}

func (data *Data) collectTypeDefinitions(src, target span.Span) {
	data.Definitions[src] = Definition{
		Src:    src,
		Def:    target,
		IsType: true,
	}
}

func (data *Data) collectDefinitionNames(src span.Span, name string) {
	d := data.Definitions[src]
	d.Name = name
	data.Definitions[src] = d
}

func (data *Data) collectHighlights(src span.Span, expected []span.Span) {
	// Declaring a highlight in a test file: @highlight(src, expected1, expected2)
	data.Highlights[src] = append(data.Highlights[src], expected...)
}

func (data *Data) collectReferences(src span.Span, expected []span.Span) {
	data.References[src] = expected
}

func (data *Data) collectRenames(src span.Span, newText string) {
	data.Renames[src] = newText
}

func (data *Data) collectPrepareRenames(src span.Span, rng span.Range, placeholder string) {
	m, err := data.Mapper(src.URI())
	if err != nil {
		data.t.Fatal(err)
	}
	// Convert range to span and then to protocol.Range.
	spn, err := rng.Span()
	if err != nil {
		data.t.Fatal(err)
	}
	prng, err := m.Range(spn)
	if err != nil {
		data.t.Fatal(err)
	}
	data.PrepareRenames[src] = &source.PrepareItem{
		Range: prng,
		Text:  placeholder,
	}
}

// collectSymbols is responsible for collecting @symbol annotations.
func (data *Data) collectSymbols(name string, spn span.Span, kind string, parentName string, siName string) {
	m, err := data.Mapper(spn.URI())
	if err != nil {
		data.t.Fatal(err)
	}
	rng, err := m.Range(spn)
	if err != nil {
		data.t.Fatal(err)
	}
	sym := protocol.DocumentSymbol{
		Name:           name,
		Kind:           protocol.ParseSymbolKind(kind),
		SelectionRange: rng,
	}
	if parentName == "" {
		data.Symbols[spn.URI()] = append(data.Symbols[spn.URI()], sym)
	} else {
		data.symbolsChildren[parentName] = append(data.symbolsChildren[parentName], sym)
	}

	// Reuse @symbol in the workspace symbols tests.
	si := protocol.SymbolInformation{
		Name: siName,
		Kind: sym.Kind,
		Location: protocol.Location{
			URI:   protocol.URIFromSpanURI(spn.URI()),
			Range: sym.SelectionRange,
		},
	}
	data.symbolInformation[spn] = si
}

func (data *Data) collectWorkspaceSymbols(typ WorkspaceSymbolsTestType) func(string, []span.Span) {
	switch typ {
	case WorkspaceSymbolsFuzzy:
		return func(query string, targets []span.Span) {
			data.FuzzyWorkspaceSymbols[query] = make([]protocol.SymbolInformation, 0, len(targets))
			for _, target := range targets {
				data.FuzzyWorkspaceSymbols[query] = append(data.FuzzyWorkspaceSymbols[query], data.symbolInformation[target])
			}
		}
	case WorkspaceSymbolsCaseSensitive:
		return func(query string, targets []span.Span) {
			data.CaseSensitiveWorkspaceSymbols[query] = make([]protocol.SymbolInformation, 0, len(targets))
			for _, target := range targets {
				data.CaseSensitiveWorkspaceSymbols[query] = append(data.CaseSensitiveWorkspaceSymbols[query], data.symbolInformation[target])
			}
		}
	default:
		return func(query string, targets []span.Span) {
			data.WorkspaceSymbols[query] = make([]protocol.SymbolInformation, 0, len(targets))
			for _, target := range targets {
				data.WorkspaceSymbols[query] = append(data.WorkspaceSymbols[query], data.symbolInformation[target])
			}
		}
	}
}

func (data *Data) collectSignatures(spn span.Span, signature string, activeParam int64) {
	data.Signatures[spn] = &protocol.SignatureHelp{
		Signatures: []protocol.SignatureInformation{
			{
				Label: signature,
			},
		},
		ActiveParameter: float64(activeParam),
	}
	// Hardcode special case to test the lack of a signature.
	if signature == "" && activeParam == 0 {
		data.Signatures[spn] = nil
	}
}

func (data *Data) collectCompletionSnippets(spn span.Span, item token.Pos, plain, placeholder string) {
	data.CompletionSnippets[spn] = append(data.CompletionSnippets[spn], CompletionSnippet{
		CompletionItem:     item,
		PlainSnippet:       plain,
		PlaceholderSnippet: placeholder,
	})
}

func (data *Data) collectLinks(spn span.Span, link string, note *expect.Note, fset *token.FileSet) {
	position := fset.Position(note.Pos)
	uri := spn.URI()
	data.Links[uri] = append(data.Links[uri], Link{
		Src:          spn,
		Target:       link,
		NotePosition: position,
	})
}

func uriName(uri span.URI) string {
	return filepath.Base(strings.TrimSuffix(uri.Filename(), ".go"))
}

func SpanName(spn span.Span) string {
	return fmt.Sprintf("%v_%v_%v", uriName(spn.URI()), spn.Start().Line(), spn.Start().Column())
}

func CopyFolderToTempDir(folder string) (string, error) {
	if _, err := os.Stat(folder); err != nil {
		return "", err
	}
	dst, err := ioutil.TempDir("", "modfile_test")
	if err != nil {
		return "", err
	}
	fds, err := ioutil.ReadDir(folder)
	if err != nil {
		return "", err
	}
	for _, fd := range fds {
		srcfp := filepath.Join(folder, fd.Name())
		stat, err := os.Stat(srcfp)
		if err != nil {
			return "", err
		}
		if !stat.Mode().IsRegular() {
			return "", fmt.Errorf("cannot copy non regular file %s", srcfp)
		}
		contents, err := ioutil.ReadFile(srcfp)
		if err != nil {
			return "", err
		}
		if err := ioutil.WriteFile(filepath.Join(dst, fd.Name()), contents, stat.Mode()); err != nil {
			return "", err
		}
	}
	return dst, nil
}

func testFolders(root string) ([]string, error) {
	// Check if this only has one test directory.
	if _, err := os.Stat(filepath.Join(filepath.FromSlash(root), "primarymod")); !os.IsNotExist(err) {
		return []string{root}, nil
	}
	folders := []string{}
	root = filepath.FromSlash(root)
	// Get all test directories that are one level deeper than root.
	if err := filepath.Walk(root, func(path string, info os.FileInfo, _ error) error {
		if !info.IsDir() {
			return nil
		}
		if filepath.Dir(path) == root {
			folders = append(folders, filepath.ToSlash(path))
		}
		return nil
	}); err != nil {
		return nil, err
	}
	return folders, nil
}

func shouldSkip(data *Data, uri span.URI) bool {
	if data.ModfileFlagAvailable {
		return false
	}
	// If the -modfile flag is not available, then we do not want to run
	// any tests on the go.mod file.
	if strings.HasSuffix(uri.Filename(), ".mod") {
		return true
	}
	// If the -modfile flag is not available, then we do not want to test any
	// uri that contains "go mod tidy".
	m, err := data.Mapper(uri)
	return err == nil && strings.Contains(string(m.Content), ", \"go mod tidy\",")
}