fix(core): allow environment variable expansion and explicit overrides for MCP servers (#18837)

2026-04-21 02:24:09 -07:00 · 2026-02-23 13:35:01 -08:00
parent 31960c3388
commit 0bc2d3ab16
7 changed files with 334 additions and 12 deletions
@@ -0,0 +1,117 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+import { expandEnvVars } from './envExpansion.js';
+
+describe('expandEnvVars', () => {
+  const defaultEnv = {
+    USER: 'morty',
+    HOME: '/home/morty',
+    TEMP: 'C:\\Temp',
+    EMPTY: '',
+  };
+
+  describe('POSIX behavior (non-Windows)', () => {
+    beforeEach(() => {
+      vi.spyOn(process, 'platform', 'get').mockReturnValue('darwin');
+    });
+
+    afterEach(() => {
+      vi.restoreAllMocks();
+    });
+
+    it.each([
+      ['$VAR (POSIX)', 'Hello $USER', defaultEnv, 'Hello morty'],
+      [
+        '${VAR} (POSIX)',
+        'Welcome to ${HOME}',
+        defaultEnv,
+        'Welcome to /home/morty',
+      ],
+      [
+        'should NOT expand %VAR% on non-Windows',
+        'Data in %TEMP%',
+        defaultEnv,
+        'Data in %TEMP%',
+      ],
+      [
+        'mixed formats (only POSIX expanded)',
+        '$USER lives in ${HOME} on %TEMP%',
+        defaultEnv,
+        'morty lives in /home/morty on %TEMP%',
+      ],
+      [
+        'missing variables (POSIX only)',
+        'Missing $UNDEFINED and ${NONE} and %MISSING%',
+        defaultEnv,
+        'Missing  and  and %MISSING%',
+      ],
+      [
+        'empty or undefined values',
+        'Value is "$EMPTY"',
+        defaultEnv,
+        'Value is ""',
+      ],
+      [
+        'original string if no variables',
+        'No vars here',
+        defaultEnv,
+        'No vars here',
+      ],
+      ['literal values like "1234"', '1234', defaultEnv, '1234'],
+      ['empty input string', '', defaultEnv, ''],
+      [
+        'complex paths',
+        '${HOME}/bin:$PATH',
+        { ...defaultEnv, PATH: '/usr/bin' },
+        '/home/morty/bin:/usr/bin',
+      ],
+    ])('should handle %s', (_, input, env, expected) => {
+      expect(expandEnvVars(input, env)).toBe(expected);
+    });
+  });
+
+  describe('Windows behavior', () => {
+    beforeEach(() => {
+      vi.spyOn(process, 'platform', 'get').mockReturnValue('win32');
+    });
+
+    afterEach(() => {
+      vi.restoreAllMocks();
+    });
+
+    it.each([
+      ['$VAR (POSIX)', 'Hello $USER', defaultEnv, 'Hello morty'],
+      [
+        '${VAR} (POSIX)',
+        'Welcome to ${HOME}',
+        defaultEnv,
+        'Welcome to /home/morty',
+      ],
+      [
+        'should expand %VAR% on Windows',
+        'Data in %TEMP%',
+        defaultEnv,
+        'Data in C:\\Temp',
+      ],
+      [
+        'mixed formats (both expanded)',
+        '$USER lives in ${HOME} on %TEMP%',
+        defaultEnv,
+        'morty lives in /home/morty on C:\\Temp',
+      ],
+      [
+        'missing variables (all expanded to empty)',
+        'Missing $UNDEFINED and ${NONE} and %MISSING%',
+        defaultEnv,
+        'Missing  and  and ',
+      ],
+    ])('should handle %s', (_, input, env, expected) => {
+      expect(expandEnvVars(input, env)).toBe(expected);
+    });
+  });
+});