test fourslash effect mount markers

.changeset/fourslash-effect-mount-markers.md

@@ -0,0 +1,5 @@
+---
+"@effect/tsgo": patch
+---
+
+Mount real Effect packages in fourslash tests when `@effect-v3` or `@effect-v4` markers are present, and cover Effect auto-import namespace behavior against the real mounted package.

_patches/018-ls-autoimport-stylepolicy.patch

@@ -1,8 +1,24 @@
+diff --git a/internal/ls/autoimport/aliasresolver.go b/internal/ls/autoimport/aliasresolver.go
+index e34b62822..b733cd122 100644
+--- a/internal/ls/autoimport/aliasresolver.go
++++ b/internal/ls/autoimport/aliasresolver.go
+@@ -219,6 +219,11 @@ func (r *aliasResolver) IsSourceFileDefaultLibrary(path tspath.Path) bool {
+ 	panic("unimplemented")
+ }
+
++// IsSourceFileFromExternalLibrary implements checker.Program.
++func (r *aliasResolver) IsSourceFileFromExternalLibrary(file *ast.SourceFile) bool {
++	return false
++}
++
+ // IsSourceFromProjectReference implements checker.Program.
+ func (r *aliasResolver) IsSourceFromProjectReference(path tspath.Path) bool {
+ 	panic("unimplemented")
 diff --git a/internal/ls/autoimport/fix.go b/internal/ls/autoimport/fix.go
-index b2107443f..bf5161047 100644
+index 991bea0db..42a0745ae 100644
 --- a/internal/ls/autoimport/fix.go
 +++ b/internal/ls/autoimport/fix.go
-@@ -74,14 +74,19 @@ func (f *Fix) Edits(
+@@ -74,14 +74,18 @@ func (f *Fix) Edits(
  	case lsproto.AutoImportFixKindAddNew:
  		var declarations []*ast.Statement
  		defaultImport := core.IfElse(f.ImportKind == lsproto.ImportKindDefault, &newImportBinding{name: f.Name, addAsTypeOnly: f.AddAsTypeOnly}, nil)
@@ -13,7 +29,7 @@ index b2107443f..bf5161047 100644
 +		}
 +		namedImports := core.IfElse(f.ImportKind == lsproto.ImportKindNamed, []*newImportBinding{{name: namedBindingName, addAsTypeOnly: f.AddAsTypeOnly}}, nil)
  		var namespaceLikeImport *newImportBinding
- 		// qualification := f.qualification()
+-		// qualification := f.qualification()
  		if f.ImportKind == lsproto.ImportKindNamespace || f.ImportKind == lsproto.ImportKindCommonJS {
 -			namespaceLikeImport = &newImportBinding{kind: f.ImportKind, name: f.Name}
 -			// if qualification != nil && qualification.namespacePref != "" {
@@ -27,7 +43,7 @@ index b2107443f..bf5161047 100644
  		}
 
  		quotePreference := lsutil.GetQuotePreference(file, preferences)
-@@ -98,9 +103,11 @@ func (f *Fix) Edits(
+@@ -98,9 +102,11 @@ func (f *Fix) Edits(
  			/*blankLineBetween*/ true,
  			preferences,
  		)
@@ -42,16 +58,18 @@ index b2107443f..bf5161047 100644
  		return tracker.GetChanges()[file.FileName()], diagnostics.Add_import_from_0.Localize(locale, f.ModuleSpecifier)
  	case lsproto.AutoImportFixKindPromoteTypeOnly:
  		promotedDeclaration := promoteFromTypeOnly(tracker, f.TypeOnlyAliasDeclaration, compilerOptions, file, preferences)
-@@ -541,7 +548,7 @@ func (v *View) GetFixes(ctx context.Context, export *Export, forJSX bool, isVali
+@@ -540,8 +546,8 @@ func (v *View) GetFixes(ctx context.Context, export *Export, forJSX bool, isVali
+ 		fixes = append(fixes, namespaceFix)
  	}
 
- 	if fix := v.tryAddToExistingImport(ctx, export, isValidTypeOnlyUseSite); fix != nil {
+-	if fix := v.tryAddToExistingImport(ctx, export, isValidTypeOnlyUseSite); fix != nil {
 -		return append(fixes, fix)
++	if fix := v.tryAddToExistingImport(ctx, export, isValidTypeOnlyUseSite, usagePosition); fix != nil {
 +		return v.applyStylePolicy(export, append(fixes, fix))
  	}
 
  	// !!! getNewImportFromExistingSpecifier - even worth it?
-@@ -549,7 +556,7 @@ func (v *View) GetFixes(ctx context.Context, export *Export, forJSX bool, isVali
+@@ -549,7 +555,7 @@ func (v *View) GetFixes(ctx context.Context, export *Export, forJSX bool, isVali
  	moduleSpecifier, moduleSpecifierKind := v.GetModuleSpecifier(export, v.preferences)
  	if moduleSpecifier == "" {
  		if len(fixes) > 0 {
@@ -60,7 +78,7 @@ index b2107443f..bf5161047 100644
  		}
  		return nil
  	}
-@@ -559,7 +566,7 @@ func (v *View) GetFixes(ctx context.Context, export *Export, forJSX bool, isVali
+@@ -559,7 +565,7 @@ func (v *View) GetFixes(ctx context.Context, export *Export, forJSX bool, isVali
  	importedSymbolHasValueMeaning := export.Flags&ast.SymbolFlagsValue != 0 || export.IsUnresolvedAlias()
  	if !importedSymbolHasValueMeaning && isJs && usagePosition != nil {
  		// For pure types in JS files, use JSDoc import type syntax
@@ -69,7 +87,7 @@ index b2107443f..bf5161047 100644
  			{
  				AutoImportFix: &lsproto.AutoImportFix{
  					Kind:            lsproto.AutoImportFixKindJsdocTypeImport,
-@@ -571,7 +578,7 @@ func (v *View) GetFixes(ctx context.Context, export *Export, forJSX bool, isVali
+@@ -571,7 +577,7 @@ func (v *View) GetFixes(ctx context.Context, export *Export, forJSX bool, isVali
  				IsReExport:          export.Target.ModuleID != export.ModuleID,
  				ModuleFileName:      export.ModuleFileName,
  			},
@@ -78,7 +96,7 @@ index b2107443f..bf5161047 100644
  	}
 
  	importKind := getImportKind(v.importingFile, export, v.program)
-@@ -587,7 +594,7 @@ func (v *View) GetFixes(ctx context.Context, export *Export, forJSX bool, isVali
+@@ -587,7 +593,7 @@ func (v *View) GetFixes(ctx context.Context, export *Export, forJSX bool, isVali
  		}
  	}
 
@@ -87,7 +105,7 @@ index b2107443f..bf5161047 100644
  		AutoImportFix: &lsproto.AutoImportFix{
  			Kind:            lsproto.AutoImportFixKindAddNew,
  			ImportKind:      importKind,
-@@ -595,11 +602,37 @@ func (v *View) GetFixes(ctx context.Context, export *Export, forJSX bool, isVali
+@@ -595,11 +601,37 @@ func (v *View) GetFixes(ctx context.Context, export *Export, forJSX bool, isVali
  			Name:            name,
  			UseRequire:      v.shouldUseRequire(),
  			AddAsTypeOnly:   addAsTypeOnly,
@@ -126,18 +144,27 @@ index b2107443f..bf5161047 100644
  }
 
  // getAddAsTypeOnly determines if an import should be type-only based on usage context
-diff --git a/internal/ls/autoimport/aliasresolver.go b/internal/ls/autoimport/aliasresolver.go
---- a/internal/ls/autoimport/aliasresolver.go
-+++ b/internal/ls/autoimport/aliasresolver.go
-@@ -220,6 +220,11 @@ func (r *aliasResolver) IsSourceFileDefaultLibrary(path tspath.Path) bool {
- 	panic("unimplemented")
- }
+@@ -674,6 +706,7 @@ func (v *View) tryAddToExistingImport(
+ 	ctx context.Context,
+ 	export *Export,
+ 	isValidTypeOnlyUseSite bool,
++	usagePosition *lsproto.Position,
+ ) *Fix {
+ 	existingImports := v.getExistingImports(ctx)
+ 	matchingDeclarations := existingImports.Get(export.ModuleID)
+@@ -711,6 +744,7 @@ func (v *View) tryAddToExistingImport(
+ 						ImportIndex:     int32(existingImport.index),
+ 						ModuleSpecifier: existingImport.moduleSpecifier,
+ 						AddAsTypeOnly:   addAsTypeOnly,
++						UsagePosition:   usagePosition,
+ 					},
+ 				}
+ 				// Variable declarations are never type-only.
+@@ -759,6 +793,7 @@ func (v *View) tryAddToExistingImport(
+ 				ImportIndex:     int32(existingImport.index),
+ 				ModuleSpecifier: existingImport.moduleSpecifier,
+ 				AddAsTypeOnly:   addAsTypeOnly,
++				UsagePosition:   usagePosition,
+ 			},
+ 		}
 
-+// IsSourceFileFromExternalLibrary implements checker.Program.
-+func (r *aliasResolver) IsSourceFileFromExternalLibrary(file *ast.SourceFile) bool {
-+	return false
-+}
-+
- // IsSourceFromProjectReference implements checker.Program.
- func (r *aliasResolver) IsSourceFromProjectReference(path tspath.Path) bool {
- 	panic("unimplemented")

etstesthooks/init.go

@@ -11,11 +11,12 @@ func init() {
 	fourslash.RegisterPrepareTestFSCallback(prepareTestFS)
 }
 
-// prepareTestFS detects Effect imports in test files and mounts real Effect packages.
-// It checks for a // @effect-v3 marker at the start of any file to choose the library version.
+// prepareTestFS detects Effect imports or explicit version markers in test files
+// and mounts real Effect packages into the fourslash VFS.
 func prepareTestFS(testfs map[string]any) {
 	hasEffectImport := false
 	hasV3Marker := false
+	hasV4Marker := false
 	for _, v := range testfs {
 		content, ok := v.(string)
 		if !ok {
@@ -27,8 +28,11 @@ func prepareTestFS(testfs map[string]any) {
 		if strings.HasPrefix(content, "// @effect-v3") || strings.Contains(content, "\n// @effect-v3") {
 			hasV3Marker = true
 		}
+		if strings.HasPrefix(content, "// @effect-v4") || strings.Contains(content, "\n// @effect-v4") {
+			hasV4Marker = true
+		}
 	}
-	if !hasEffectImport {
+	if !hasEffectImport && !hasV3Marker && !hasV4Marker {
 		return
 	}
 	version := bundledeffect.EffectV4

etstesthooks/init_test.go

@@ -0,0 +1,71 @@
+package etstesthooks
+
+import (
+	"strings"
+	"testing"
+	"testing/fstest"
+)
+
+func TestPrepareTestFSMountsEffectForV4MarkerWithoutImport(t *testing.T) {
+	t.Parallel()
+
+	testfs := map[string]any{
+		"/main.ts": "// @effect-v4\nconst value = 1\n",
+	}
+
+	prepareTestFS(testfs)
+
+	assertMountedEffect(t, testfs)
+	assertSourcePackageName(t, testfs, "effect-v4-tests")
+}
+
+func TestPrepareTestFSMountsEffectForV3MarkerWithoutImport(t *testing.T) {
+	t.Parallel()
+
+	testfs := map[string]any{
+		"/main.ts": "// @effect-v3\nconst value = 1\n",
+	}
+
+	prepareTestFS(testfs)
+
+	assertMountedEffect(t, testfs)
+	assertSourcePackageName(t, testfs, "effect-v3-tests")
+}
+
+func TestPrepareTestFSDoesNotMountWithoutImportOrMarker(t *testing.T) {
+	t.Parallel()
+
+	testfs := map[string]any{
+		"/main.ts": "const value = 1\n",
+	}
+
+	prepareTestFS(testfs)
+
+	if _, ok := testfs["/.src/package.json"]; ok {
+		t.Fatal("expected no mounted Effect package without import or marker")
+	}
+	if _, ok := testfs["/node_modules/effect/package.json"]; ok {
+		t.Fatal("expected no mounted effect package without import or marker")
+	}
+}
+
+func assertMountedEffect(t *testing.T, testfs map[string]any) {
+	t.Helper()
+	if _, ok := testfs["/.src/package.json"]; !ok {
+		t.Fatal("expected mounted /.src/package.json")
+	}
+	if _, ok := testfs["/node_modules/effect/package.json"]; !ok {
+		t.Fatal("expected mounted /node_modules/effect/package.json")
+	}
+}
+
+func assertSourcePackageName(t *testing.T, testfs map[string]any, want string) {
+	t.Helper()
+	file, ok := testfs["/.src/package.json"].(*fstest.MapFile)
+	if !ok {
+		t.Fatal("expected /.src/package.json to be a fstest.MapFile")
+	}
+	if !strings.Contains(string(file.Data), want) {
+		t.Fatalf("expected /.src/package.json to contain %q, got %q", want, string(file.Data))
+	}
+}

internal/autoimportstyle/stylepolicy.go

@@ -25,19 +25,40 @@ func NewFixTransformer(resolved *etscore.ResolvedEffectPluginOptions) autoimport
 	}
 	return func(export *autoimport.Export, fixes []*autoimport.Fix) []*autoimport.Fix {
 		rewritten := make([]*autoimport.Fix, 0, len(fixes))
+		hasUseNamespace := make(map[string]bool)
 		for _, fix := range fixes {
 			adjusted := sp.Apply(export, fix)
 			if adjusted != nil {
+				if adjusted.Kind == lsproto.AutoImportFixKindUseNamespace {
+					hasUseNamespace[namespaceFixKey(adjusted)] = true
+				}
 				rewritten = append(rewritten, adjusted)
 			}
 		}
+		if len(hasUseNamespace) != 0 {
+			filtered := rewritten[:0]
+			for _, fix := range rewritten {
+				if fix.Kind == lsproto.AutoImportFixKindAddNew && fix.ImportKind == lsproto.ImportKindNamespace && hasUseNamespace[namespaceFixKey(fix)] {
+					continue
+				}
+				filtered = append(filtered, fix)
+			}
+			rewritten = filtered
+		}
 		if len(rewritten) == 0 {
 			return nil
 		}
 		return rewritten
 	}
 }
 
+func namespaceFixKey(fix *autoimport.Fix) string {
+	if fix == nil {
+		return ""
+	}
+	return fix.ModuleSpecifier + "\x00" + fix.NamespacePrefix
+}
+
 // newStylePolicy creates a stylePolicy from the given resolved options.
 // Package names are lowercased for case-insensitive matching.
 func newStylePolicy(resolved *etscore.ResolvedEffectPluginOptions) *stylePolicy {
@@ -75,8 +96,8 @@ func (sp *stylePolicy) Apply(export *autoimport.Export, fix *autoimport.Fix) *au
 		return fix
 	}
 
-	// Only rewrite AddNew fixes
-	if fix.Kind != lsproto.AutoImportFixKindAddNew {
+	// Only rewrite new imports or additions to existing imports.
+	if fix.Kind != lsproto.AutoImportFixKindAddNew && fix.Kind != lsproto.AutoImportFixKindAddToExisting {
 		return fix
 	}
 

internal/autoimportstyle/stylepolicy_test.go

@@ -104,6 +104,34 @@ func TestApplyNamespaceRewrite(t *testing.T) {
 	}
 }
 
+func TestApplyNamespaceRewriteFromAddToExisting(t *testing.T) {
+	t.Parallel()
+	sp := newStylePolicy(&etscore.ResolvedEffectPluginOptions{
+		NamespaceImportPackages: []string{"effect"},
+	})
+
+	export := makeExport("effect", "effect/testing/TestClock", "")
+	fix := makeAddNewFix(lsproto.ImportKindNamed, "effect/testing/TestClock", "testClockWith")
+	fix.Kind = lsproto.AutoImportFixKindAddToExisting
+
+	result := sp.Apply(export, fix)
+	if result == nil {
+		t.Fatal("expected non-nil result")
+	}
+	if result.Kind != lsproto.AutoImportFixKindAddNew {
+		t.Errorf("expected rewrite to AddNew, got %v", result.Kind)
+	}
+	if result.ImportKind != lsproto.ImportKindNamespace {
+		t.Errorf("expected ImportKindNamespace, got %v", result.ImportKind)
+	}
+	if result.ModuleSpecifier != "effect/testing/TestClock" {
+		t.Errorf("expected module specifier 'effect/testing/TestClock', got %q", result.ModuleSpecifier)
+	}
+	if result.NamespacePrefix != "TestClock" {
+		t.Errorf("expected namespace prefix 'TestClock', got %q", result.NamespacePrefix)
+	}
+}
+
 func TestApplyNamespaceRewriteWithAlias(t *testing.T) {
 	t.Parallel()
 	sp := newStylePolicy(&etscore.ResolvedEffectPluginOptions{
@@ -403,3 +431,32 @@ func TestNewFixTransformerAppliesPolicy(t *testing.T) {
 		t.Errorf("expected ImportKindNamespace, got %v", result[0].ImportKind)
 	}
 }
+
+func TestNewFixTransformerPrefersExistingNamespaceUse(t *testing.T) {
+	t.Parallel()
+	transformer := NewFixTransformer(&etscore.ResolvedEffectPluginOptions{
+		NamespaceImportPackages: []string{"effect"},
+	})
+	if transformer == nil {
+		t.Fatal("expected non-nil transformer")
+	}
+
+	export := makeExport("effect", "effect/testing/TestClock", "")
+	useNamespace := &autoimport.Fix{AutoImportFix: &lsproto.AutoImportFix{
+		Kind:            lsproto.AutoImportFixKindUseNamespace,
+		ImportKind:      lsproto.ImportKindNamespace,
+		ModuleSpecifier: "effect/testing/TestClock",
+		Name:            "testClockWith",
+		NamespacePrefix: "TestClock",
+	}}
+	addToExisting := makeAddNewFix(lsproto.ImportKindNamed, "effect/testing/TestClock", "testClockWith")
+	addToExisting.Kind = lsproto.AutoImportFixKindAddToExisting
+
+	result := transformer(export, []*autoimport.Fix{useNamespace, addToExisting})
+	if len(result) != 1 {
+		t.Fatalf("expected 1 fix, got %d", len(result))
+	}
+	if result[0].Kind != lsproto.AutoImportFixKindUseNamespace {
+		t.Fatalf("expected UseNamespace fix, got %v", result[0].Kind)
+	}
+}