diff --git a/spec/observables/generate-spec.ts b/spec/observables/generate-spec.ts
index 127271891f..6f4578c826 100644
--- a/spec/observables/generate-spec.ts
+++ b/spec/observables/generate-spec.ts
@@ -1,169 +1,215 @@
+/** @prettier */
 import { TestScheduler } from 'rxjs/testing';
 import { expect } from 'chai';
-import { expectObservable } from '../helpers/marble-testing';
-import { generate, Subscriber } from 'rxjs';
+import { generate } from 'rxjs';
 import { take } from 'rxjs/operators';
 import { SafeSubscriber } from 'rxjs/internal/Subscriber';
-
-declare const rxTestScheduler: TestScheduler;
+import { observableMatcher } from '../helpers/observableMatcher';
 
 function err(): any {
   throw 'error';
 }
 
 describe('generate', () => {
-  it('should complete if condition does not meet', () => {
-    const source = generate(1, x => false, x => x + 1);
-    const expected = '|';
+  let rxTestScheduler: TestScheduler;
 
-    expectObservable(source).toBe(expected);
+  beforeEach(() => {
+    rxTestScheduler = new TestScheduler(observableMatcher);
   });
 
-  it('should produce first value immediately', () => {
-    const source = generate(1, x => x == 1, x => x + 1);
-    const expected = '(1|)';
+  it('should complete if condition does not meet', () => {
+    rxTestScheduler.run(({ expectObservable }) => {
+      const source = generate(
+        1,
+        (x) => false,
+        (x) => x + 1
+      );
+      const expected = '|';
+
+      expectObservable(source).toBe(expected);
+    });
+  });
 
-    expectObservable(source).toBe(expected, { '1': 1 });
+  it('should produce first value immediately', () => {
+    rxTestScheduler.run(({ expectObservable }) => {
+      const source = generate(
+        1,
+        (x) => x == 1,
+        (x) => x + 1
+      );
+      const expected = '(1|)';
+
+      expectObservable(source).toBe(expected, { '1': 1 });
+    });
   });
 
   it('should produce all values synchronously', () => {
-    const source = generate(1, x => x < 3, x => x + 1);
-    const expected = '(12|)';
-
-    expectObservable(source).toBe(expected, { '1': 1, '2': 2 });
+    rxTestScheduler.run(({ expectObservable }) => {
+      const source = generate(
+        1,
+        (x) => x < 3,
+        (x) => x + 1
+      );
+      const expected = '(12|)';
+
+      expectObservable(source).toBe(expected, { '1': 1, '2': 2 });
+    });
   });
 
   it('should use result selector', () => {
-    const source = generate(1, x => x < 3, x => x + 1, x => (x + 1).toString());
-    const expected = '(23|)';
-
-    expectObservable(source).toBe(expected);
+    rxTestScheduler.run(({ expectObservable }) => {
+      const source = generate(
+        1,
+        (x) => x < 3,
+        (x) => x + 1,
+        (x) => (x + 1).toString()
+      );
+      const expected = '(23|)';
+
+      expectObservable(source).toBe(expected);
+    });
   });
 
   it('should allow omit condition', () => {
-    const source = generate({
-      initialState: 1,
-      iterate: x => x + 1,
-      resultSelector: (x: number) => x.toString()
-    }).pipe(
-      take(5)
-    );
-    const expected = '(12345|)';
-
-    expectObservable(source).toBe(expected);
+    rxTestScheduler.run(({ expectObservable }) => {
+      const source = generate({
+        initialState: 1,
+        iterate: (x) => x + 1,
+        resultSelector: (x: number) => x.toString(),
+      }).pipe(take(5));
+      const expected = '(12345|)';
+
+      expectObservable(source).toBe(expected);
+    });
   });
 
   it('should stop producing when unsubscribed', () => {
-    const source = generate(1, x => x < 4, x => x + 1);
+    const source = generate(
+      1,
+      (x) => x < 4,
+      (x) => x + 1
+    );
     let count = 0;
-    const subscriber = new SafeSubscriber<number>(
-      x => {
-        count++;
-        if (x == 2) {
-          subscriber.unsubscribe();
-        }
+    const subscriber = new SafeSubscriber<number>((x) => {
+      count++;
+      if (x == 2) {
+        subscriber.unsubscribe();
       }
-    );
+    });
     source.subscribe(subscriber);
     expect(count).to.be.equal(2);
   });
 
   it('should accept a scheduler', () => {
-    const source = generate({
-      initialState: 1,
-      condition: x => x < 4,
-      iterate: x => x + 1,
-      resultSelector: (x: number) => x,
-      scheduler: rxTestScheduler
+    rxTestScheduler.run(({ expectObservable }) => {
+      const source = generate({
+        initialState: 1,
+        condition: (x) => x < 4,
+        iterate: (x) => x + 1,
+        resultSelector: (x: number) => x,
+        scheduler: rxTestScheduler,
+      });
+      const expected = '(123|)';
+
+      let count = 0;
+      source.subscribe((x) => count++);
+
+      expect(count).to.be.equal(0);
+      rxTestScheduler.flush();
+      expect(count).to.be.equal(3);
+
+      expectObservable(source).toBe(expected, { '1': 1, '2': 2, '3': 3 });
     });
-    const expected = '(123|)';
-
-    let count = 0;
-    source.subscribe(x => count++);
-
-    expect(count).to.be.equal(0);
-    rxTestScheduler.flush();
-    expect(count).to.be.equal(3);
-
-    expectObservable(source).toBe(expected, { '1': 1, '2': 2, '3': 3 });
   });
 
   it('should allow minimal possible options', () => {
-    const source = generate({
-      initialState: 1,
-      iterate: x => x * 2
-    }).pipe(
-      take(3)
-    );
-    const expected = '(124|)';
-
-    expectObservable(source).toBe(expected, { '1': 1, '2': 2, '4': 4 });
+    rxTestScheduler.run(({ expectObservable }) => {
+      const source = generate({
+        initialState: 1,
+        iterate: (x) => x * 2,
+      }).pipe(take(3));
+      const expected = '(124|)';
+
+      expectObservable(source).toBe(expected, { '1': 1, '2': 2, '4': 4 });
+    });
   });
 
   it('should emit error if result selector throws', () => {
-    const source = generate({
-      initialState: 1,
-      iterate: x => x * 2,
-      resultSelector: err
+    rxTestScheduler.run(({ expectObservable }) => {
+      const source = generate({
+        initialState: 1,
+        iterate: (x) => x * 2,
+        resultSelector: err,
+      });
+      const expected = '(#)';
+
+      expectObservable(source).toBe(expected);
     });
-    const expected = '(#)';
-
-    expectObservable(source).toBe(expected);
   });
 
   it('should emit error if result selector throws on scheduler', () => {
-    const source = generate({
-      initialState: 1,
-      iterate: x => x * 2,
-      resultSelector: err,
-      scheduler: rxTestScheduler
+    rxTestScheduler.run(({ expectObservable }) => {
+      const source = generate({
+        initialState: 1,
+        iterate: (x) => x * 2,
+        resultSelector: err,
+        scheduler: rxTestScheduler,
+      });
+      const expected = '(#)';
+
+      expectObservable(source).toBe(expected);
     });
-    const expected = '(#)';
-
-    expectObservable(source).toBe(expected);
   });
 
   it('should emit error after first value if iterate function throws', () => {
-    const source = generate({
-      initialState: 1,
-      iterate: err
+    rxTestScheduler.run(({ expectObservable }) => {
+      const source = generate({
+        initialState: 1,
+        iterate: err,
+      });
+      const expected = '(1#)';
+
+      expectObservable(source).toBe(expected, { '1': 1 });
     });
-    const expected = '(1#)';
-
-    expectObservable(source).toBe(expected, { '1': 1 });
   });
 
   it('should emit error after first value if iterate function throws on scheduler', () => {
-    const source = generate({
-      initialState: 1,
-      iterate: err,
-      scheduler: rxTestScheduler
+    rxTestScheduler.run(({ expectObservable }) => {
+      const source = generate({
+        initialState: 1,
+        iterate: err,
+        scheduler: rxTestScheduler,
+      });
+      const expected = '(1#)';
+
+      expectObservable(source).toBe(expected, { '1': 1 });
     });
-    const expected = '(1#)';
-
-    expectObservable(source).toBe(expected, { '1': 1 });
   });
 
   it('should emit error if condition function throws', () => {
-    const source = generate({
-      initialState: 1,
-      iterate: x => x + 1,
-      condition: err
+    rxTestScheduler.run(({ expectObservable }) => {
+      const source = generate({
+        initialState: 1,
+        iterate: (x) => x + 1,
+        condition: err,
+      });
+      const expected = '(#)';
+
+      expectObservable(source).toBe(expected);
     });
-    const expected = '(#)';
-
-    expectObservable(source).toBe(expected);
   });
 
   it('should emit error if condition function throws on scheduler', () => {
-    const source = generate({
-      initialState: 1,
-      iterate: x => x + 1,
-      condition: err,
-      scheduler: rxTestScheduler
+    rxTestScheduler.run(({ expectObservable }) => {
+      const source = generate({
+        initialState: 1,
+        iterate: (x) => x + 1,
+        condition: err,
+        scheduler: rxTestScheduler,
+      });
+      const expected = '(#)';
+
+      expectObservable(source).toBe(expected);
     });
-    const expected = '(#)';
-
-    expectObservable(source).toBe(expected);
   });
 });