gopls/internal/golang: implement 'Go to TestXxx' CodeLens and Code Action

gopls/doc/codelenses.md

@@ -40,6 +40,17 @@ Default: on
 
 File type: Go
 
+## `go_to_test`: Go to the functions's Test, Example, Benchmark, or Fuzz declarations
+
+
+This codelens source annotates function and method declarations
+with their corresponding Test, Example, Benchmark, and Fuzz functions.
+
+
+Default: off
+
+File type: Go
+
 ## `regenerate_cgo`: Re-generate cgo declarations
 
 

gopls/internal/cache/snapshot.go

@@ -976,7 +976,7 @@ func (s *Snapshot) WorkspaceMetadata(ctx context.Context) ([]*metadata.Package,
 	defer s.mu.Unlock()
 
 	meta := make([]*metadata.Package, 0, s.workspacePackages.Len())
-	for id, _ := range s.workspacePackages.All() {
+	for id := range s.workspacePackages.All() {
 		meta = append(meta, s.meta.Packages[id])
 	}
 	return meta, nil

gopls/internal/cache/testfuncs/tests.go

@@ -8,6 +8,7 @@ import (
 	"go/ast"
 	"go/constant"
 	"go/types"
+	"iter"
 	"strings"
 	"unicode"
 	"unicode/utf8"
@@ -35,22 +36,36 @@ func (index *Index) Encode() []byte {
 	return packageCodec.Encode(index.pkg)
 }
 
-func (index *Index) All() []Result {
-	var results []Result
-	for _, file := range index.pkg.Files {
-		for _, test := range file.Tests {
-			results = append(results, test.result())
+func (index *Index) All() iter.Seq[Result] {
+	return func(yield func(Result) bool) {
+		for _, file := range index.pkg.Files {
+			for _, test := range file.Tests {
+				if !yield(test.result()) {
+					return
+				}
+			}
 		}
 	}
-	return results
 }
 
 // A Result reports a test function
 type Result struct {
 	Location protocol.Location // location of the test
 	Name     string            // name of the test
+	Type     TestType          // type of the test
+	Subtest  bool
 }
 
+type TestType int
+
+const (
+	TypeInvalid TestType = iota
+	TypeTest
+	TypeBenchmark
+	TypeFuzz
+	TypeExample
+)
+
 // NewIndex returns a new index of method-set information for all
 // package-level types in the specified package.
 func NewIndex(files []*parsego.File, info *types.Info) *Index {
@@ -84,15 +99,16 @@ func (b *indexBuilder) build(files []*parsego.File, info *types.Info) *Index {
 				continue
 			}
 
-			isTest, isExample := isTestOrExample(obj)
-			if !isTest && !isExample {
+			testType := getTestType(obj)
+			if testType == TypeInvalid {
 				continue
 			}
 
 			var t gobTest
 			t.Name = decl.Name.Name
 			t.Location.URI = file.URI
 			t.Location.Range, _ = file.NodeRange(decl)
+			t.Type = testType
 
 			i, ok := b.fileIndex[t.Location.URI]
 			if !ok {
@@ -105,7 +121,8 @@ func (b *indexBuilder) build(files []*parsego.File, info *types.Info) *Index {
 			b.visited[obj] = true
 
 			// Check for subtests
-			if isTest {
+			switch testType {
+			case TypeTest, TypeBenchmark, TypeFuzz:
 				b.Files[i].Tests = append(b.Files[i].Tests, b.findSubtests(t, decl.Type, decl.Body, file, files, info)...)
 			}
 		}
@@ -168,6 +185,8 @@ func (b *indexBuilder) findSubtests(parent gobTest, typ *ast.FuncType, body *ast
 		t.Name = b.uniqueName(parent.Name, rewrite(constant.StringVal(val)))
 		t.Location.URI = file.URI
 		t.Location.Range, _ = file.NodeRange(call)
+		t.Type = parent.Type
+		t.Subtest = true
 		tests = append(tests, t)
 
 		fn, typ, body := findFunc(files, info, body, call.Args[1])
@@ -182,7 +201,8 @@ func (b *indexBuilder) findSubtests(parent gobTest, typ *ast.FuncType, body *ast
 		}
 
 		// Never recurse if the second argument is a top-level test function
-		if isTest, _ := isTestOrExample(fn); isTest {
+		switch getTestType(fn) {
+		case TypeTest, TypeBenchmark, TypeFuzz:
 			continue
 		}
 
@@ -258,30 +278,35 @@ func findFunc(files []*parsego.File, info *types.Info, body *ast.BlockStmt, expr
 	return nil, nil, nil
 }
 
-// isTestOrExample reports whether the given func is a testing func or an
-// example func (or neither). isTestOrExample returns (true, false) for testing
-// funcs, (false, true) for example funcs, and (false, false) otherwise.
-func isTestOrExample(fn *types.Func) (isTest, isExample bool) {
+// getTestType reports the test type of the given function.
+func getTestType(fn *types.Func) TestType {
 	sig := fn.Type().(*types.Signature)
-	if sig.Params().Len() == 0 &&
-		sig.Results().Len() == 0 {
-		return false, isTestName(fn.Name(), "Example")
+	if sig.Params().Len() == 0 && sig.Results().Len() == 0 {
+		if isTestName(fn.Name(), "Example") {
+			return TypeExample
+		}
+		return TypeInvalid
 	}
 
 	kind, ok := testKind(sig)
 	if !ok {
-		return false, false
+		return TypeInvalid
 	}
 	switch kind.Name() {
 	case "T":
-		return isTestName(fn.Name(), "Test"), false
+		if isTestName(fn.Name(), "Test") {
+			return TypeTest
+		}
 	case "B":
-		return isTestName(fn.Name(), "Benchmark"), false
+		if isTestName(fn.Name(), "Benchmark") {
+			return TypeBenchmark
+		}
 	case "F":
-		return isTestName(fn.Name(), "Fuzz"), false
-	default:
-		return false, false // "can't happen" (see testKind)
+		if isTestName(fn.Name(), "Fuzz") {
+			return TypeFuzz
+		}
 	}
+	return TypeInvalid
 }
 
 // isTestName reports whether name is a valid test name for the test kind
@@ -352,6 +377,8 @@ type gobFile struct {
 type gobTest struct {
 	Location protocol.Location // location of the test
 	Name     string            // name of the test
+	Type     TestType          // type of the test
+	Subtest  bool
 }
 
 func (t *gobTest) result() Result {

gopls/internal/doc/api.json

@@ -1917,6 +1917,12 @@
 							"Default": "true",
 							"Status": ""
 						},
+						{
+							"Name": "\"go_to_test\"",
+							"Doc": "`\"go_to_test\"`: Go to the functions's Test, Example, Benchmark, or Fuzz declarations\n\nThis codelens source annotates function and method declarations\nwith their corresponding Test, Example, Benchmark, and Fuzz functions.\n",
+							"Default": "false",
+							"Status": ""
+						},
 						{
 							"Name": "\"regenerate_cgo\"",
 							"Doc": "`\"regenerate_cgo\"`: Re-generate cgo declarations\n\nThis codelens source annotates an `import \"C\"` declaration\nwith a command to re-run the [cgo\ncommand](https://pkg.go.dev/cmd/cgo) to regenerate the\ncorresponding Go declarations.\n\nUse this after editing the C code in comments attached to\nthe import, or in C header files included by it.\n",
@@ -2104,6 +2110,14 @@
 			"Default": true,
 			"Status": ""
 		},
+		{
+			"FileType": "Go",
+			"Lens": "go_to_test",
+			"Title": "Go to the functions's Test, Example, Benchmark, or Fuzz declarations",
+			"Doc": "\nThis codelens source annotates function and method declarations\nwith their corresponding Test, Example, Benchmark, and Fuzz functions.\n",
+			"Default": false,
+			"Status": ""
+		},
 		{
 			"FileType": "Go",
 			"Lens": "regenerate_cgo",