fix(uninstall): allow removing the last installed version

src/cmd/uninstall.go

@@ -24,7 +24,10 @@ This command removes a specific version of a runtime from your system.
 The version directory and all its contents will be deleted.
 
 Safety features:
-  - Cannot uninstall the currently active global version
+  - Cannot uninstall the global version while other versions are installed
+    (set a different global version first)
+  - Uninstalling the only installed version clears the global version, so
+    the runtime's commands fall back to your system PATH
   - Prompts for confirmation before deletion
   - Automatically regenerates shims after uninstall
 
@@ -58,23 +61,41 @@ Examples:
 			return
 		}
 
-		// Check if this is the currently active global version
+		// The global version can only go while nothing else could replace
+		// it: with other versions installed the user picks the new global
+		// first, and with none the global setting is cleared afterwards.
+		// Install sets the first version as global, so refusing outright
+		// would leave the last version impossible to remove.
+		clearGlobal := false
 		globalVersion, err := provider.GlobalVersion()
 		if err == nil && globalVersion == version {
-			ui.Error("Cannot uninstall the currently active global version")
-			ui.Info("Current global version: v%s", globalVersion)
-			ui.Info("Set a different global version first: dtvem global %s <version>", runtimeName)
-			return
+			installed, err := provider.ListInstalled()
+			if err != nil {
+				ui.Error("Could not list installed %s versions: %v", provider.DisplayName(), err)
+				return
+			}
+			if others := otherVersions(installed, version); len(others) > 0 {
+				ui.Error("Cannot uninstall the global version while other versions are installed")
+				ui.Info("Current global version: v%s", globalVersion)
+				ui.Info("Other installed versions: %s", strings.Join(others, ", "))
+				ui.Info("Set a different global version first: dtvem global %s <version>", runtimeName)
+				return
+			}
+			clearGlobal = true
 		}
 
-		// Check if this is the currently active local version
-		localVersion, err := provider.LocalVersion()
-		if err == nil && localVersion == version {
+		// Check if a project file pins this version for the working directory
+		if source := localPinSource(provider.Name(), version); source != "" {
 			ui.Warning("This is the currently active local version in this directory")
-			ui.Info("Local version file: dtvem.config.json")
+			ui.Info("Local version file: %s", source)
 			ui.Info("You may need to update or remove it after uninstalling")
 		}
 
+		if clearGlobal {
+			ui.Warning("v%s is the global %s version and the only one installed", version, provider.DisplayName())
+			ui.Info("The global %s version will be cleared", provider.DisplayName())
+		}
+
 		// Prompt for confirmation (unless --yes flag is provided)
 		if !uninstallYes {
 			fmt.Printf("\n")
@@ -104,6 +125,15 @@ Examples:
 
 		spinner.Success(fmt.Sprintf("%s v%s removed", provider.DisplayName(), version))
 
+		if clearGlobal {
+			if err := config.UnsetGlobalVersion(provider.Name()); err != nil {
+				ui.Warning("Could not clear the global %s version: %v", provider.DisplayName(), err)
+				ui.Info("Remove the %q entry from %s", provider.Name(), config.GlobalConfigPath())
+			} else {
+				ui.Info("Cleared the global %s version", provider.DisplayName())
+			}
+		}
+
 		// Regenerate shims
 		shimSpinner := ui.NewSpinner("Regenerating shims...")
 		shimSpinner.Start()
@@ -125,6 +155,30 @@ Examples:
 	},
 }
 
+// localPinSource returns the file that sets version for runtimeName in the
+// working directory or one of its parents, or "" when none does. The global
+// config does not count: provider.LocalVersion falls back to it, which made
+// the global version look pinned locally everywhere.
+func localPinSource(runtimeName, version string) string {
+	res, err := config.Resolve(runtimeName)
+	if err != nil || res.Version != version || res.Source == config.GlobalConfigPath() {
+		return ""
+	}
+	return res.Source
+}
+
+// otherVersions returns the installed versions other than version, in the
+// order given.
+func otherVersions(installed []runtime.InstalledVersion, version string) []string {
+	var others []string
+	for _, iv := range installed {
+		if iv.Version.Raw != version {
+			others = append(others, iv.Version.Raw)
+		}
+	}
+	return others
+}
+
 func init() {
 	uninstallCmd.Flags().BoolVarP(&uninstallYes, "yes", "y", false, "Skip confirmation prompt")
 	rootCmd.AddCommand(uninstallCmd)

src/cmd/uninstall_test.go

@@ -3,10 +3,12 @@ package cmd
 import (
 	"os"
 	"path/filepath"
+	"slices"
 	"strings"
 	"testing"
 
 	"github.com/CodingWithCalvin/dtvem.cli/src/internal/config"
+	"github.com/CodingWithCalvin/dtvem.cli/src/internal/runtime"
 )
 
 func TestUninstallCommand_VersionStripping(t *testing.T) {
@@ -208,3 +210,130 @@ func TestUninstallCommand_ConfirmationResponse(t *testing.T) {
 		})
 	}
 }
+
+func TestOtherVersions(t *testing.T) {
+	installed := func(versions ...string) []runtime.InstalledVersion {
+		out := make([]runtime.InstalledVersion, 0, len(versions))
+		for _, v := range versions {
+			out = append(out, runtime.InstalledVersion{Version: runtime.NewVersion(v)})
+		}
+		return out
+	}
+
+	tests := []struct {
+		name      string
+		installed []runtime.InstalledVersion
+		version   string
+		want      []string
+	}{
+		{
+			name:      "Only version installed",
+			installed: installed("3.4.7"),
+			version:   "3.4.7",
+			want:      nil,
+		},
+		{
+			name:      "Other versions installed",
+			installed: installed("22.0.0", "22.12.0", "25.2.0"),
+			version:   "25.2.0",
+			want:      []string{"22.0.0", "22.12.0"},
+		},
+		{
+			name:      "Version not in the list",
+			installed: installed("3.12.12", "3.9.9"),
+			version:   "3.8.9",
+			want:      []string{"3.12.12", "3.9.9"},
+		},
+		{
+			name:      "Nothing installed",
+			installed: nil,
+			version:   "3.4.7",
+			want:      nil,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := otherVersions(tt.installed, tt.version)
+			if !slices.Equal(got, tt.want) {
+				t.Errorf("otherVersions(%v, %q) = %v, want %v", tt.installed, tt.version, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestLocalPinSource(t *testing.T) {
+	tmp := t.TempDir()
+	t.Setenv("DTVEM_ROOT", filepath.Join(tmp, "dtvem"))
+	config.ResetPathsCache()
+	t.Cleanup(config.ResetPathsCache)
+
+	if err := os.MkdirAll(config.RuntimeVersionPath("ruby", "3.4.7"), 0755); err != nil {
+		t.Fatalf("Failed to create installed version: %v", err)
+	}
+	if err := config.SetGlobalVersion("ruby", "3.4.7"); err != nil {
+		t.Fatalf("SetGlobalVersion() setup error: %v", err)
+	}
+
+	pinned := filepath.Join(tmp, "pinned")
+	unpinned := filepath.Join(tmp, "unpinned")
+	for _, dir := range []string{pinned, unpinned} {
+		if err := os.MkdirAll(dir, 0755); err != nil {
+			t.Fatalf("Failed to create %s: %v", dir, err)
+		}
+	}
+	versionFile := filepath.Join(pinned, ".ruby-version")
+	if err := os.WriteFile(versionFile, []byte("3.4\n"), 0644); err != nil {
+		t.Fatalf("Failed to write .ruby-version: %v", err)
+	}
+
+	originalDir, err := os.Getwd()
+	if err != nil {
+		t.Fatalf("Failed to get working directory: %v", err)
+	}
+	t.Cleanup(func() { _ = os.Chdir(originalDir) })
+
+	chdir := func(dir string) {
+		t.Helper()
+		if err := os.Chdir(dir); err != nil {
+			t.Fatalf("Failed to change directory: %v", err)
+		}
+	}
+
+	t.Run("Global version is not a local pin", func(t *testing.T) {
+		chdir(unpinned)
+		if got := localPinSource("ruby", "3.4.7"); got != "" {
+			t.Errorf("localPinSource() with only a global version = %q, want \"\"", got)
+		}
+	})
+
+	t.Run("Project file pins the version", func(t *testing.T) {
+		chdir(pinned)
+		got := localPinSource("ruby", "3.4.7")
+		if got == "" || !sameFile(t, got, versionFile) {
+			t.Errorf("localPinSource() = %q, want %q", got, versionFile)
+		}
+	})
+
+	t.Run("Project file pins a different version", func(t *testing.T) {
+		chdir(pinned)
+		if got := localPinSource("ruby", "3.3.0"); got != "" {
+			t.Errorf("localPinSource() for another version = %q, want \"\"", got)
+		}
+	})
+}
+
+// sameFile reports whether two paths name the same file. Temp paths can
+// differ only by symlinks (macOS reports /var/... as /private/var/...).
+func sameFile(t *testing.T, a, b string) bool {
+	t.Helper()
+	ai, err := os.Stat(a)
+	if err != nil {
+		t.Fatalf("Failed to stat %s: %v", a, err)
+	}
+	bi, err := os.Stat(b)
+	if err != nil {
+		t.Fatalf("Failed to stat %s: %v", b, err)
+	}
+	return os.SameFile(ai, bi)
+}

src/internal/config/version.go

@@ -253,6 +253,40 @@ func SetGlobalVersion(runtimeName, version string) error {
 	return os.WriteFile(configPath, data, 0644)
 }
 
+// UnsetGlobalVersion removes a runtime's entry from the global config, so
+// the runtime has no global version. Other runtimes' entries are kept.
+// It does nothing when there is no global config or no entry for the
+// runtime, and returns an error rather than rewriting a config it cannot
+// parse.
+func UnsetGlobalVersion(runtimeName string) error {
+	configPath := GlobalConfigPath()
+
+	data, err := os.ReadFile(configPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return fmt.Errorf("failed to read global config: %w", err)
+	}
+
+	config := make(RuntimesConfig)
+	if err := json.Unmarshal(data, &config); err != nil {
+		return fmt.Errorf("failed to parse global config %s: %w", configPath, err)
+	}
+
+	if _, ok := config[runtimeName]; !ok {
+		return nil
+	}
+	delete(config, runtimeName)
+
+	data, err = json.MarshalIndent(config, "", "  ")
+	if err != nil {
+		return err
+	}
+
+	return os.WriteFile(configPath, data, 0644)
+}
+
 // SetLocalVersion sets the local version for a runtime in the current directory
 func SetLocalVersion(runtimeName, version string) error {
 	configDir := LocalConfigDir()