Do not create a proxy agent if proxy url is empty string. (#8580)

Author: JoeRobich

src/packageManager/proxy.ts

@@ -21,7 +21,7 @@ function getSystemProxyURL(requestURL: Url): string | undefined {
 export function getProxyAgent(requestURL: Url, proxy: string, strictSSL: boolean): Agent | undefined {
     const proxyURL = proxy.length > 0 ? proxy : getSystemProxyURL(requestURL);
 
-    if (proxyURL === undefined) {
+    if (proxyURL === undefined || proxyURL.length === 0) {
         return undefined;
     }
 

test/omnisharp/omnisharpUnitTests/packages/proxy.test.ts

@@ -0,0 +1,52 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { describe, test, expect, beforeAll, afterAll, beforeEach } from '@jest/globals';
+import { getProxyAgent } from '../../../../src/packageManager/proxy';
+import url from 'url';
+
+describe(`${getProxyAgent.name}`, () => {
+    let originalHttpProxy: string | undefined;
+    let originalHttpsProxy: string | undefined;
+
+    const requestUrl = url.parse('https://github.com');
+
+    beforeAll(() => {
+        originalHttpProxy = process.env.HTTP_PROXY;
+        originalHttpsProxy = process.env.HTTPS_PROXY;
+    });
+
+    afterAll(() => {
+        if (originalHttpProxy !== undefined) {
+            process.env.HTTP_PROXY = originalHttpProxy;
+        } else {
+            delete process.env.HTTP_PROXY;
+        }
+
+        if (originalHttpsProxy !== undefined) {
+            process.env.HTTPS_PROXY = originalHttpsProxy;
+        } else {
+            delete process.env.HTTPS_PROXY;
+        }
+    });
+
+    beforeEach(() => {
+        delete process.env.HTTP_PROXY;
+        delete process.env.HTTPS_PROXY;
+    });
+
+    test('Returns `undefined` for empty proxy url and `undefined` HTTP_PROXY env', async () => {
+        const result = getProxyAgent(requestUrl, /* proxy */ '', /* strictSSL */ false);
+        expect(result).toBe(undefined);
+    });
+
+    test('Returns `undefined` for empty proxy url and empty HTTP_PROXY env', async () => {
+        process.env.HTTP_PROXY = '';
+        process.env.HTTPS_PROXY = '';
+
+        const result = getProxyAgent(requestUrl, /* proxy */ '', /* strictSSL */ false);
+        expect(result).toBe(undefined);
+    });
+});