fix(@angular-devkit/build-angular): do not process regular expressions in proxy config when using Vite

This commit enables proxies to have a RegExp as context when using Vite. See: https://vitejs.dev/config/server-options#server-proxy

Closes angular#26970

Author: alan-agius4

packages/angular_devkit/build_angular/src/builders/dev-server/tests/options/proxy-config_spec.ts

@@ -12,7 +12,7 @@ import { executeOnceAndFetch } from '../execute-fetch';
 import { describeServeBuilder } from '../jasmine-helpers';
 import { BASE_OPTIONS, DEV_SERVER_BUILDER_INFO } from '../setup';
 
-describeServeBuilder(executeDevServer, DEV_SERVER_BUILDER_INFO, (harness, setupTarget) => {
+describeServeBuilder(executeDevServer, DEV_SERVER_BUILDER_INFO, (harness, setupTarget, isVite) => {
   describe('option: "proxyConfig"', () => {
     beforeEach(async () => {
       setupTarget(harness);
@@ -232,6 +232,69 @@ describeServeBuilder(executeDevServer, DEV_SERVER_BUILDER_INFO, (harness, setupT
         }),
       );
     });
+
+    /**
+     * ****************************************************************************************************
+     * ********************************** Below only Vite specific tests **********************************
+     * ****************************************************************************************************
+     */
+    if (!isVite) {
+      return;
+    }
+
+    describe('when using Vite', () => {
+      it('proxies support regexp as context', async () => {
+        harness.useTarget('serve', {
+          ...BASE_OPTIONS,
+          proxyConfig: 'proxy.config.json',
+        });
+
+        const proxyServer = createProxyServer();
+        try {
+          await new Promise<void>((resolve) => proxyServer.listen(0, '127.0.0.1', resolve));
+          const proxyAddress = proxyServer.address() as import('net').AddressInfo;
+
+          await harness.writeFiles({
+            'proxy.config.json': `
+              { "^/api/.*": { "target": "http://127.0.0.1:${proxyAddress.port}" } }
+            `,
+          });
+
+          const { result, response } = await executeOnceAndFetch(harness, '/api/test');
+
+          expect(result?.success).toBeTrue();
+          expect(await response?.text()).toContain('TEST_API_RETURN');
+        } finally {
+          await new Promise<void>((resolve) => proxyServer.close(() => resolve()));
+        }
+      });
+
+      it('proxies support negated regexp as context', async () => {
+        harness.useTarget('serve', {
+          ...BASE_OPTIONS,
+          proxyConfig: 'proxy.config.json',
+        });
+
+        const proxyServer = createProxyServer();
+        try {
+          await new Promise<void>((resolve) => proxyServer.listen(0, '127.0.0.1', resolve));
+          const proxyAddress = proxyServer.address() as import('net').AddressInfo;
+
+          await harness.writeFiles({
+            'proxy.config.json': `
+              { "^\\/(?!something).*": { "target": "http://127.0.0.1:${proxyAddress.port}" } }
+            `,
+          });
+
+          const { result, response } = await executeOnceAndFetch(harness, '/api/test');
+
+          expect(result?.success).toBeTrue();
+          expect(await response?.text()).toContain('TEST_API_RETURN');
+        } finally {
+          await new Promise<void>((resolve) => proxyServer.close(() => resolve()));
+        }
+      });
+    });
   });
 });
 

packages/angular_devkit/build_angular/src/utils/load-proxy-config.ts

@@ -128,7 +128,7 @@ function normalizeProxyConfiguration(
 
   // TODO: Consider upstreaming glob support
   for (const key of Object.keys(normalizedProxy)) {
-    if (isDynamicPattern(key)) {
+    if (key[0] !== '^' && isDynamicPattern(key)) {
       const { output } = parseGlob(key);
       normalizedProxy[`^${output}$`] = normalizedProxy[key];
       delete normalizedProxy[key];