Address feedback

Author: devversion

test/karma-test-shim.js

@@ -92,12 +92,24 @@ function configureTestBed() {
       testingBrowser.platformBrowserDynamicTesting()
     );
 
-    applyAngularTestingPatches(testBed);
+    patchTestBedToDestroyFixturesAfterEveryTest(testBed);
   });
 }
 
-/** Applies patches and workarounds to Angular's testing package. */
-function applyAngularTestingPatches(testBed) {
+/**
+ * Monkey-patches TestBed.resetTestingModule such that any errors that occur during component
+ * destruction are thrown instead of silently logged. Also runs TestBed.resetTestingModule after
+ * each unit test.
+ *
+ * Without this patch, the combination of two behaviors is problematic for Angular Material:
+ * - TestBed.resetTestingModule catches errors thrown on fixture destruction and logs them without
+ *     the errors ever being thrown. This means that any component errors that occur in ngOnDestroy
+ *     can encounter errors silently and still pass unit tests.
+ * - TestBed.resetTestingModule is only called *before* a test is run, meaning that even *if* the
+ *    aforementioned errors were thrown, they would be reported for the wrong test (the test that's
+ *    about to start, not the test that just finished).
+ */
+function patchTestBedToDestroyFixturesAfterEveryTest(testBed) {
   // Original resetTestingModule function of the TestBed.
   var _resetTestingModule = testBed.resetTestingModule;
 
@@ -114,9 +126,9 @@ function applyAngularTestingPatches(testBed) {
     }
   };
 
-  // Angular's testing package resets the testing module before each test. This is bad because
-  // it doesn't allow developers to see what test actually failed. Fixing this by resetting
-  // the testing module after each test.
+  // Angular's testing package resets the testing module before each test. This doesn't work well
+  // for us because it doesn't allow developers to see what test actually failed.
+  // Fixing this by resetting the testing module after each test.
   // https://github.com/angular/angular/blob/master/packages/core/testing/src/before_each.ts#L25
   afterEach(function() {
     testBed.resetTestingModule();