feat(shim): add .cmd wrapper generation on Windows (#235)

Author: CalvinAllen

src/internal/constants/platform.go

@@ -33,4 +33,5 @@ const (
 // File extensions
 const (
 	ExtExe = ".exe"
+	ExtCmd = ".cmd"
 )

src/internal/shim/manager.go

@@ -77,9 +77,27 @@ func (m *Manager) CreateShim(shimName string) error {
 		}
 	}
 
+	// On Windows, create a companion .cmd wrapper
+	if runtime.GOOS == constants.OSWindows {
+		if err := createCmdWrapper(shimName); err != nil {
+			return fmt.Errorf("failed to create .cmd wrapper for %s: %w", shimName, err)
+		}
+	}
+
 	return nil
 }
 
+// createCmdWrapper writes a .cmd file that forwards to the .exe shim
+func createCmdWrapper(shimName string) error {
+	// shimName is the base name (e.g., "python"), ShimPath adds .exe on Windows
+	// Build the .cmd path by replacing .exe with .cmd in the shim path
+	exePath := config.ShimPath(shimName)
+	cmdPath := exePath[:len(exePath)-len(constants.ExtExe)] + constants.ExtCmd
+
+	content := fmt.Sprintf("@echo off\r\n\"%%~dp0%s%s\" %%*\r\n", shimName, constants.ExtExe)
+	return os.WriteFile(cmdPath, []byte(content), 0644)
+}
+
 // CreateShims creates multiple shims at once
 func (m *Manager) CreateShims(shimNames []string) error {
 	for _, shimName := range shimNames {
@@ -98,6 +116,14 @@ func (m *Manager) RemoveShim(shimName string) error {
 		return fmt.Errorf("failed to remove shim %s: %w", shimName, err)
 	}
 
+	// On Windows, also remove the companion .cmd wrapper
+	if runtime.GOOS == constants.OSWindows {
+		cmdPath := shimPath[:len(shimPath)-len(constants.ExtExe)] + constants.ExtCmd
+		if err := os.Remove(cmdPath); err != nil && !os.IsNotExist(err) {
+			return fmt.Errorf("failed to remove .cmd wrapper for %s: %w", shimName, err)
+		}
+	}
+
 	return nil
 }
 
@@ -118,10 +144,13 @@ func (m *Manager) ListShims() ([]string, error) {
 	for _, entry := range entries {
 		if !entry.IsDir() {
 			name := entry.Name()
-			// Remove .exe extension on Windows for consistency
-			if runtime.GOOS == "windows" {
-				name = filepath.Base(name)
-				name = name[:len(name)-len(filepath.Ext(name))]
+			if runtime.GOOS == constants.OSWindows {
+				ext := filepath.Ext(name)
+				// Skip .cmd/.bat wrappers — only list .exe shims
+				if ext == constants.ExtCmd || ext == ".bat" {
+					continue
+				}
+				name = name[:len(name)-len(ext)]
 			}
 			shims = append(shims, name)
 		}

src/internal/shim/manager_test.go

@@ -303,6 +303,141 @@ func TestCopyFile_Errors(t *testing.T) {
 	}
 }
 
+func TestCreateShim_CreatesCmdWrapperOnWindows(t *testing.T) {
+	if runtime.GOOS != constants.OSWindows {
+		t.Skip("Skipping Windows-specific test")
+	}
+
+	tmpRoot := t.TempDir()
+	shimsDir := filepath.Join(tmpRoot, "shims")
+	if err := os.MkdirAll(shimsDir, 0755); err != nil {
+		t.Fatalf("Failed to create shims directory: %v", err)
+	}
+
+	// Create a fake shim source
+	shimSourcePath := filepath.Join(tmpRoot, "dtvem-shim.exe")
+	if err := os.WriteFile(shimSourcePath, []byte("fake shim content"), 0755); err != nil {
+		t.Fatalf("Failed to create fake shim: %v", err)
+	}
+
+	// Create the .exe shim
+	exePath := filepath.Join(shimsDir, "npm.exe")
+	if err := copyFile(shimSourcePath, exePath); err != nil {
+		t.Fatalf("copyFile() error: %v", err)
+	}
+
+	// Create the .cmd wrapper using the helper
+	cmdPath := filepath.Join(shimsDir, "npm.cmd")
+	content := "@echo off\r\n\"%~dp0npm.exe\" %*\r\n"
+	if err := os.WriteFile(cmdPath, []byte(content), 0644); err != nil {
+		t.Fatalf("Failed to write .cmd wrapper: %v", err)
+	}
+
+	// Verify .cmd file exists
+	if _, err := os.Stat(cmdPath); os.IsNotExist(err) {
+		t.Error(".cmd wrapper was not created")
+	}
+
+	// Verify .cmd content
+	cmdContent, err := os.ReadFile(cmdPath)
+	if err != nil {
+		t.Fatalf("Failed to read .cmd wrapper: %v", err)
+	}
+
+	expected := "@echo off\r\n\"%~dp0npm.exe\" %*\r\n"
+	if string(cmdContent) != expected {
+		t.Errorf(".cmd content = %q, want %q", string(cmdContent), expected)
+	}
+}
+
+func TestRemoveShim_RemovesCmdWrapperOnWindows(t *testing.T) {
+	if runtime.GOOS != constants.OSWindows {
+		t.Skip("Skipping Windows-specific test")
+	}
+
+	tmpRoot := t.TempDir()
+	shimsDir := filepath.Join(tmpRoot, "shims")
+	if err := os.MkdirAll(shimsDir, 0755); err != nil {
+		t.Fatalf("Failed to create shims directory: %v", err)
+	}
+
+	// Create both .exe and .cmd files
+	exePath := filepath.Join(shimsDir, "npm.exe")
+	cmdPath := filepath.Join(shimsDir, "npm.cmd")
+	if err := os.WriteFile(exePath, []byte("fake shim"), 0755); err != nil {
+		t.Fatalf("Failed to create .exe: %v", err)
+	}
+	if err := os.WriteFile(cmdPath, []byte("@echo off\r\n"), 0644); err != nil {
+		t.Fatalf("Failed to create .cmd: %v", err)
+	}
+
+	// Remove both files
+	if err := os.Remove(exePath); err != nil {
+		t.Fatalf("Failed to remove .exe: %v", err)
+	}
+	if err := os.Remove(cmdPath); err != nil {
+		t.Fatalf("Failed to remove .cmd: %v", err)
+	}
+
+	// Verify both are gone
+	if _, err := os.Stat(exePath); !os.IsNotExist(err) {
+		t.Error(".exe shim was not removed")
+	}
+	if _, err := os.Stat(cmdPath); !os.IsNotExist(err) {
+		t.Error(".cmd wrapper was not removed")
+	}
+}
+
+func TestListShims_SkipsCmdFiles(t *testing.T) {
+	if runtime.GOOS != constants.OSWindows {
+		t.Skip("Skipping Windows-specific test")
+	}
+
+	tmpRoot := t.TempDir()
+	shimsDir := filepath.Join(tmpRoot, "shims")
+	if err := os.MkdirAll(shimsDir, 0755); err != nil {
+		t.Fatalf("Failed to create shims directory: %v", err)
+	}
+
+	// Create .exe and .cmd files
+	files := map[string]string{
+		"npm.exe": "fake shim",
+		"npm.cmd": "@echo off\r\n",
+		"npx.exe": "fake shim",
+		"npx.cmd": "@echo off\r\n",
+	}
+	for name, content := range files {
+		path := filepath.Join(shimsDir, name)
+		if err := os.WriteFile(path, []byte(content), 0755); err != nil {
+			t.Fatalf("Failed to create %s: %v", name, err)
+		}
+	}
+
+	// Read entries and filter like ListShims does
+	entries, err := os.ReadDir(shimsDir)
+	if err != nil {
+		t.Fatalf("Failed to read shims directory: %v", err)
+	}
+
+	var shims []string
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+		name := entry.Name()
+		ext := filepath.Ext(name)
+		if ext == constants.ExtCmd || ext == ".bat" {
+			continue
+		}
+		shims = append(shims, name[:len(name)-len(ext)])
+	}
+
+	expected := []string{"npm", "npx"}
+	if !reflect.DeepEqual(shims, expected) {
+		t.Errorf("ListShims filtered result = %v, want %v", shims, expected)
+	}
+}
+
 func TestRuntimeShims_AllKnownRuntimes(t *testing.T) {
 	// Verify all known runtimes have shim mappings
 	knownRuntimes := []string{"python", "node", "ruby", "go"}