🖼️ refactor: Enhance Env Extraction & Agent Image Handling (#6131)

* refactor: use new image output format for agents using DALL-E tools

* refactor: Enhance image fetching with proxy support and adjust logging placement in DALL-E 3 integration

* refactor: Enhance StableDiffusionAPI to support agent-specific return values and display message for generated images

* refactor: Add unit test execution for librechat-mcp in backend review workflow

* refactor: Update environment variable extraction logic, export from serpate module to avoid circular refs, and remove deprecated tests

* refactor: Add unit tests for environment variable extraction and enhance StdioOptionsSchema to process env variables

packages/data-provider/specs/utils.spec.ts

@@ -0,0 +1,129 @@
+import { extractEnvVariable } from '../src/utils';
+
+describe('Environment Variable Extraction', () => {
+  const originalEnv = process.env;
+
+  beforeEach(() => {
+    process.env = {
+      ...originalEnv,
+      TEST_API_KEY: 'test-api-key-value',
+      ANOTHER_SECRET: 'another-secret-value',
+    };
+  });
+
+  afterEach(() => {
+    process.env = originalEnv;
+  });
+
+  describe('extractEnvVariable (original tests)', () => {
+    test('should return the value of the environment variable', () => {
+      process.env.TEST_VAR = 'test_value';
+      expect(extractEnvVariable('${TEST_VAR}')).toBe('test_value');
+    });
+
+    test('should return the original string if the envrionment variable is not defined correctly', () => {
+      process.env.TEST_VAR = 'test_value';
+      expect(extractEnvVariable('${ TEST_VAR }')).toBe('${ TEST_VAR }');
+    });
+
+    test('should return the original string if environment variable is not set', () => {
+      expect(extractEnvVariable('${NON_EXISTENT_VAR}')).toBe('${NON_EXISTENT_VAR}');
+    });
+
+    test('should return the original string if it does not contain an environment variable', () => {
+      expect(extractEnvVariable('some_string')).toBe('some_string');
+    });
+
+    test('should handle empty strings', () => {
+      expect(extractEnvVariable('')).toBe('');
+    });
+
+    test('should handle strings without variable format', () => {
+      expect(extractEnvVariable('no_var_here')).toBe('no_var_here');
+    });
+
+    /** No longer the expected behavior; keeping for reference */
+    test.skip('should not process multiple variable formats', () => {
+      process.env.FIRST_VAR = 'first';
+      process.env.SECOND_VAR = 'second';
+      expect(extractEnvVariable('${FIRST_VAR} and ${SECOND_VAR}')).toBe(
+        '${FIRST_VAR} and ${SECOND_VAR}',
+      );
+    });
+  });
+
+  describe('extractEnvVariable function', () => {
+    it('should extract environment variables from exact matches', () => {
+      expect(extractEnvVariable('${TEST_API_KEY}')).toBe('test-api-key-value');
+      expect(extractEnvVariable('${ANOTHER_SECRET}')).toBe('another-secret-value');
+    });
+
+    it('should extract environment variables from strings with prefixes', () => {
+      expect(extractEnvVariable('prefix-${TEST_API_KEY}')).toBe('prefix-test-api-key-value');
+    });
+
+    it('should extract environment variables from strings with suffixes', () => {
+      expect(extractEnvVariable('${TEST_API_KEY}-suffix')).toBe('test-api-key-value-suffix');
+    });
+
+    it('should extract environment variables from strings with both prefixes and suffixes', () => {
+      expect(extractEnvVariable('prefix-${TEST_API_KEY}-suffix')).toBe(
+        'prefix-test-api-key-value-suffix',
+      );
+    });
+
+    it('should not match invalid patterns', () => {
+      expect(extractEnvVariable('$TEST_API_KEY')).toBe('$TEST_API_KEY');
+      expect(extractEnvVariable('{TEST_API_KEY}')).toBe('{TEST_API_KEY}');
+      expect(extractEnvVariable('TEST_API_KEY')).toBe('TEST_API_KEY');
+    });
+  });
+
+  describe('extractEnvVariable', () => {
+    it('should extract environment variable values', () => {
+      expect(extractEnvVariable('${TEST_API_KEY}')).toBe('test-api-key-value');
+      expect(extractEnvVariable('${ANOTHER_SECRET}')).toBe('another-secret-value');
+    });
+
+    it('should return the original string if environment variable is not found', () => {
+      expect(extractEnvVariable('${NON_EXISTENT_VAR}')).toBe('${NON_EXISTENT_VAR}');
+    });
+
+    it('should return the original string if no environment variable pattern is found', () => {
+      expect(extractEnvVariable('plain-string')).toBe('plain-string');
+    });
+  });
+
+  describe('extractEnvVariable space trimming', () => {
+    beforeEach(() => {
+      process.env.HELLO = 'world';
+      process.env.USER = 'testuser';
+    });
+
+    it('should extract the value when string contains only an environment variable with surrounding whitespace', () => {
+      expect(extractEnvVariable('        ${HELLO}        ')).toBe('world');
+      expect(extractEnvVariable('  ${HELLO}  ')).toBe('world');
+      expect(extractEnvVariable('\t${HELLO}\n')).toBe('world');
+    });
+
+    it('should preserve content when variable is part of a larger string', () => {
+      expect(extractEnvVariable('Hello ${USER}!')).toBe('Hello testuser!');
+      expect(extractEnvVariable('  Hello ${USER}!  ')).toBe('Hello testuser!');
+    });
+
+    it('should not handle multiple variables', () => {
+      expect(extractEnvVariable('${HELLO} ${USER}')).toBe('${HELLO} ${USER}');
+      expect(extractEnvVariable('  ${HELLO}   ${USER}  ')).toBe('${HELLO}   ${USER}');
+    });
+
+    it('should handle undefined variables', () => {
+      expect(extractEnvVariable('        ${UNDEFINED_VAR}        ')).toBe('${UNDEFINED_VAR}');
+    });
+
+    it('should handle mixed content correctly', () => {
+      expect(extractEnvVariable('Welcome, ${USER}!\nYour message: ${HELLO}')).toBe(
+        'Welcome, testuser!\nYour message: world',
+      );
+    });
+  });
+});