Use XDF_CONFIG_HOME for fish config when available

Fixes #1158

Author: Tyriar

src/features/terminal/shells/fish/fishStartup.ts

@@ -19,10 +19,14 @@ async function isFishInstalled(): Promise<boolean> {
     }
 }
 
-async function getFishProfile(): Promise<string> {
-    const homeDir = os.homedir();
-    // Fish configuration is typically at ~/.config/fish/config.fish
-    const profilePath = path.join(homeDir, '.config', 'fish', 'config.fish');
+/**
+ * Resolve the Fish configuration profile path, honoring XDG_CONFIG_HOME when set.
+ */
+export async function getFishProfile(): Promise<string> {
+    const xdgConfigHome = process.env.XDG_CONFIG_HOME?.trim() ?? '';
+    const baseConfigDir = xdgConfigHome.length > 0 ? xdgConfigHome : path.join(os.homedir(), '.config');
+    // Fish configuration is typically at $XDG_CONFIG_HOME/fish/config.fish or ~/.config/fish/config.fish
+    const profilePath = path.join(baseConfigDir, 'fish', 'config.fish');
     traceInfo(`SHELL: fish profile found at: ${profilePath}`);
     return profilePath;
 }

src/test/features/terminal/shells/fishStartup.unit.test.ts

@@ -0,0 +1,41 @@
+import * as assert from 'assert';
+import * as os from 'os';
+import * as path from 'path';
+import * as sinon from 'sinon';
+
+import { getFishProfile } from '../../../../features/terminal/shells/fish/fishStartup';
+
+suite('Fish Startup', () => {
+    let originalXdgConfigHome: string | undefined;
+
+    setup(() => {
+        originalXdgConfigHome = process.env.XDG_CONFIG_HOME;
+    });
+
+    teardown(() => {
+        if (originalXdgConfigHome === undefined) {
+            delete process.env.XDG_CONFIG_HOME;
+        } else {
+            process.env.XDG_CONFIG_HOME = originalXdgConfigHome;
+        }
+        sinon.restore();
+    });
+
+    test('getFishProfile uses XDG_CONFIG_HOME when set', async () => {
+        const xdgConfigHome = path.join('test', 'xdg');
+        process.env.XDG_CONFIG_HOME = xdgConfigHome;
+
+        const profilePath = await getFishProfile();
+
+        assert.strictEqual(profilePath, path.join(xdgConfigHome, 'fish', 'config.fish'));
+    });
+
+    test('getFishProfile falls back to ~/.config when XDG_CONFIG_HOME is empty', async () => {
+        process.env.XDG_CONFIG_HOME = '   ';
+        const homeDir = os.homedir();
+
+        const profilePath = await getFishProfile();
+
+        assert.strictEqual(profilePath, path.join(homeDir, '.config', 'fish', 'config.fish'));
+    });
+});