Modifies unit tests to accommodate event ID check (#270)

* Modifies unit tests to accommodate event ID check

* Extracts event ID from outgoing URL

* Addresses comments

Checks that the URL is rejected by the callback matcher without the event ID.

Author: protocol86

Example/Auth/Tests/FIRPhoneAuthProviderTests.m

@@ -393,8 +393,14 @@ - (void)testVerifyPhoneNumberUIDelegate {
     // `callbackMatcher` is at index 4
     [invocation getArgument:&unretainedArgument atIndex:4];
     FIRAuthURLCallbackMatcher callbackMatcher = unretainedArgument;
-    NSURLComponents *originalComponents =
-        [[NSURLComponents alloc] initWithString:kFakeRedirectURLStringWithReCAPTCHAToken];
+    NSMutableString *redirectURL =
+        [NSMutableString stringWithString:kFakeRedirectURLStringWithReCAPTCHAToken];
+    // Verify that the URL is rejected by the callback matcher without the event ID.
+    XCTAssertFalse(callbackMatcher([NSURL URLWithString:redirectURL]));
+    [redirectURL appendString:@"%26eventId%3D"];
+    [redirectURL appendString:params[@"eventId"]];
+    NSURLComponents *originalComponents = [[NSURLComponents alloc] initWithString:redirectURL];
+    // Verify that the URL is accepted by the callback matcher with the matching event ID.
     XCTAssertTrue(callbackMatcher([originalComponents URL]));
     NSURLComponents *components = [originalComponents copy];
     components.query = @"https";