[Identity] Different approach for testing the Arc feature, instead of mock-fs (Azure#15571)

Recently we found an issue on our CI build for Node 16.3.0, which boiled down to one unit test specific to Identity: Azure#15547

After some investigation, it is clear that Node 16.3.0 has some incompatibility with mock-fs: tschaub/mock-fs#332

In the mean time, to add this test again, we can simply create a file, point to it and delete it at the end. This should work in all versions of Node, and it means one less dev-dependency for us.

Author: sadasant

sdk/identity/identity/package.json

@@ -126,7 +126,6 @@
     "util": "^0.12.1",
     "sinon": "^9.0.2",
     "@types/sinon": "^9.0.4",
-    "mock-fs": "^4.10.4",
     "typedoc": "0.15.2"
   }
 }

sdk/identity/identity/test/internal/node/managedIdentityCredential.spec.ts

@@ -13,16 +13,16 @@ import { MockAuthHttpClient, MockAuthHttpClientOptions, assertRejects } from "..
 import { OAuthErrorResponse } from "../../../src/client/errors";
 import Sinon from "sinon";
 import { imdsMsiRetryConfig } from "../../../src/credentials/managedIdentityCredential/imdsMsi";
+import { mkdtempSync, rmdirSync, unlinkSync, writeFileSync } from "fs";
+import { join } from "path";
+import { tmpdir } from "os";
 
 interface AuthRequestDetails {
   requests: WebResource[];
   token: AccessToken | null;
 }
 
 describe("ManagedIdentityCredential", function() {
-  // There are no types available for this dependency, at least at the time this test file was written.
-  // eslint-disable-next-line @typescript-eslint/no-require-imports
-  const mockFs = require("mock-fs");
   let envCopy: string = "";
   let sandbox: Sinon.SinonSandbox;
   let clock: Sinon.SinonFakeTimers;
@@ -42,7 +42,6 @@ describe("ManagedIdentityCredential", function() {
     });
   });
   afterEach(() => {
-    mockFs.restore();
     const env = JSON.parse(envCopy);
     process.env.IDENTITY_ENDPOINT = env.IDENTITY_ENDPOINT;
     process.env.IDENTITY_HEADER = env.IDENTITY_HEADER;
@@ -338,71 +337,75 @@ describe("ManagedIdentityCredential", function() {
     }
   });
 
-  // This fails on ubuntu1804_16x_node on Node version 16.3.0
-  it.skip("sends an authorization request correctly in an Azure Arc environment", async () => {
+  it("sends an authorization request correctly in an Azure Arc environment", async function() {
     // Trigger Azure Arc behavior by setting environment variables
 
     process.env.IMDS_ENDPOINT = "https://endpoint";
     process.env.IDENTITY_ENDPOINT = "https://endpoint";
 
-    const filePath = "path/to/file";
+    // eslint-disable-next-line @typescript-eslint/no-invalid-this
+    const testTitle = this.test?.title || `test-Date.time()`;
+    const tempDir = mkdtempSync(join(tmpdir(), testTitle));
+    const tempFile = join(tempDir, testTitle);
     const key = "challenge key";
-
-    mockFs({
-      [`${filePath}`]: key
-    });
-
-    const authDetails = await getMsiTokenAuthRequest(["https://service/.default"], undefined, {
-      authResponse: [
-        {
-          status: 401,
-          headers: new HttpHeaders({
-            "www-authenticate": `we don't pay much attention about this format=${filePath}`
-          })
-        },
-        {
-          status: 200,
-          parsedBody: {
-            token: "token",
-            expires_in: 1
+    writeFileSync(tempFile, key, { encoding: "utf8" });
+
+    try {
+      const authDetails = await getMsiTokenAuthRequest(["https://service/.default"], undefined, {
+        authResponse: [
+          {
+            status: 401,
+            headers: new HttpHeaders({
+              "www-authenticate": `we don't pay much attention about this format=${tempFile}`
+            })
+          },
+          {
+            status: 200,
+            parsedBody: {
+              token: "token",
+              expires_in: 1
+            }
           }
-        }
-      ]
-    });
-
-    // File request
-    const validationRequest = authDetails.requests[0];
-    assert.ok(validationRequest.query, "No query string parameters on request");
+        ]
+      });
 
-    assert.equal(validationRequest.method, "GET");
-    assert.equal(decodeURIComponent(validationRequest.query!["resource"]), "https://service");
+      // File request
+      const validationRequest = authDetails.requests[0];
+      assert.ok(validationRequest.query, "No query string parameters on request");
 
-    assert.ok(
-      validationRequest.url.startsWith(process.env.IDENTITY_ENDPOINT),
-      "URL does not start with expected host and path"
-    );
+      assert.equal(validationRequest.method, "GET");
+      assert.equal(decodeURIComponent(validationRequest.query!["resource"]), "https://service");
 
-    // Authorization request, which comes after getting the file path, for now at least.
-    const authRequest = authDetails.requests[1];
-    assert.ok(authRequest.query, "No query string parameters on request");
+      assert.ok(
+        validationRequest.url.startsWith(process.env.IDENTITY_ENDPOINT),
+        "URL does not start with expected host and path"
+      );
 
-    assert.equal(authRequest.method, "GET");
-    assert.equal(decodeURIComponent(authRequest.query!["resource"]), "https://service");
+      // Authorization request, which comes after getting the file path, for now at least.
+      const authRequest = authDetails.requests[1];
+      assert.ok(authRequest.query, "No query string parameters on request");
 
-    assert.ok(
-      authRequest.url.startsWith(process.env.IDENTITY_ENDPOINT),
-      "URL does not start with expected host and path"
-    );
+      assert.equal(authRequest.method, "GET");
+      assert.equal(decodeURIComponent(authRequest.query!["resource"]), "https://service");
 
-    assert.equal(authRequest.headers.get("Authorization"), `Basic ${key}`);
-    if (authDetails.token) {
-      // We use Date.now underneath.
-      assert.equal(
-        Math.floor(authDetails.token.expiresOnTimestamp / 1000000),
-        Math.floor(Date.now() / 1000000)
+      assert.ok(
+        authRequest.url.startsWith(process.env.IDENTITY_ENDPOINT),
+        "URL does not start with expected host and path"
       );
-    } else {
-      assert.fail("No token was returned!");
+
+      assert.equal(authRequest.headers.get("Authorization"), `Basic ${key}`);
+      if (authDetails.token) {
+        // We use Date.now underneath.
+        assert.equal(
+          Math.floor(authDetails.token.expiresOnTimestamp / 1000000),
+          Math.floor(Date.now() / 1000000)
+        );
+      } else {
+        assert.fail("No token was returned!");
+      }
+    } finally {
+      unlinkSync(tempFile);
+      rmdirSync(tempDir);
     }
   });