From 4b6893369353ac9bb2648259c037fdd33abda0a7 Mon Sep 17 00:00:00 2001
From: Nicholas Jamieson <nicholas@cartant.com>
Date: Thu, 17 May 2018 18:40:32 +1000
Subject: [PATCH 1/2] test(TestScheduler): add failing test

---
 spec/schedulers/TestScheduler-spec.ts | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/spec/schedulers/TestScheduler-spec.ts b/spec/schedulers/TestScheduler-spec.ts
index 848255f358..11daad56a3 100644
--- a/spec/schedulers/TestScheduler-spec.ts
+++ b/spec/schedulers/TestScheduler-spec.ts
@@ -1,5 +1,6 @@
 import { expect } from 'chai';
 import { hot, cold, expectObservable, expectSubscriptions, time } from '../helpers/marble-testing';
+import { AsyncScheduler } from 'rxjs/internal/scheduler/AsyncScheduler';
 import { TestScheduler } from 'rxjs/testing';
 import { Observable, NEVER, EMPTY, Subject, of, concat, merge, Notification } from 'rxjs';
 import { delay, debounceTime, concatMap } from 'rxjs/operators';
@@ -441,5 +442,25 @@ describe('TestScheduler', () => {
         done();
       });
     });
+
+    it('should restore changes upon thrown errors', () => {
+      const testScheduler = new TestScheduler(assertDeepEquals);
+
+      const frameTimeFactor = TestScheduler['frameTimeFactor'];
+      const maxFrames = testScheduler.maxFrames;
+      const runMode = testScheduler['runMode'];
+      const delegate = AsyncScheduler.delegate;
+
+      try {
+        testScheduler.run(() => {
+          throw new Error('kaboom!');
+        });
+      } catch { /* empty */ }
+
+      expect(TestScheduler['frameTimeFactor']).to.equal(frameTimeFactor);
+      expect(testScheduler.maxFrames).to.equal(maxFrames);
+      expect(testScheduler['runMode']).to.equal(runMode);
+      expect(AsyncScheduler.delegate).to.equal(delegate);
+    });
   });
 });

From 27cb9b60a3399955c8df1405090b81d22be4315e Mon Sep 17 00:00:00 2001
From: Nicholas Jamieson <nicholas@cartant.com>
Date: Thu, 17 May 2018 18:41:10 +1000
Subject: [PATCH 2/2] fix(TestScheduler): restore run changes upon error

---
 src/internal/testing/TestScheduler.ts | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/internal/testing/TestScheduler.ts b/src/internal/testing/TestScheduler.ts
index 329b3f3319..60474b3078 100644
--- a/src/internal/testing/TestScheduler.ts
+++ b/src/internal/testing/TestScheduler.ts
@@ -378,14 +378,15 @@ export class TestScheduler extends VirtualTimeScheduler {
       expectObservable: this.expectObservable.bind(this),
       expectSubscriptions: this.expectSubscriptions.bind(this),
     };
-    const ret = callback(helpers);
-    this.flush();
-
-    TestScheduler.frameTimeFactor = prevFrameTimeFactor;
-    this.maxFrames = prevMaxFrames;
-    this.runMode = false;
-    AsyncScheduler.delegate = undefined;
-
-    return ret;
+    try {
+      const ret = callback(helpers);
+      this.flush();
+      return ret;
+    } finally {
+      TestScheduler.frameTimeFactor = prevFrameTimeFactor;
+      this.maxFrames = prevMaxFrames;
+      this.runMode = false;
+      AsyncScheduler.delegate = undefined;
+    }
   }
 }