Convert clearStack from a function to an object

spec/core/StackClearerSpec.js

@@ -0,0 +1,265 @@
+describe('StackClearer', function() {
+  it('works in an integrationy way', function(done) {
+    const { clearStack } = privateUnderTest.getStackClearer(
+      jasmineUnderTest.getGlobal()
+    );
+
+    clearStack(function() {
+      done();
+    });
+  });
+
+  describe('in Safari', function() {
+    usesQueueMicrotaskWithSetTimeout(function() {
+      return {
+        navigator: {
+          userAgent:
+            'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_6) AppleWebKit/605.0.8 (KHTML, like Gecko) Version/15.1 Safari/605.0.8'
+        },
+        // queueMicrotask should be used even though MessageChannel is present
+        MessageChannel: fakeMessageChannel
+      };
+    });
+
+    it('uses MessageChannel to reduce setTimeout clamping', function() {
+      const fakeChannel = fakeMessageChannel();
+      spyOn(fakeChannel.port2, 'postMessage');
+      const queueMicrotask = jasmine.createSpy('queueMicrotask');
+      const global = {
+        navigator: {
+          userAgent:
+            'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_6) AppleWebKit/605.0.8 (KHTML, like Gecko) Version/15.1 Safari/605.0.8'
+        },
+        MessageChannel: function() {
+          return fakeChannel;
+        },
+        queueMicrotask
+      };
+
+      const { clearStack } = privateUnderTest.getStackClearer(global);
+
+      for (let i = 0; i < 9; i++) {
+        clearStack(function() {});
+      }
+
+      expect(fakeChannel.port2.postMessage).not.toHaveBeenCalled();
+
+      clearStack(function() {});
+
+      expect(fakeChannel.port2.postMessage).toHaveBeenCalledTimes(1);
+    });
+  });
+
+  describe("in WebKit (Playwright's build for Windows)", function() {
+    usesQueueMicrotaskWithSetTimeout(function() {
+      return {
+        navigator: {
+          userAgent:
+            'Mozilla/5.0 (Windows NT 6.2; Win64; x64) AppleWebKit/605.1.15 (KHTML, like Gecko)'
+        },
+        // queueMicrotask should be used even though MessageChannel is present
+        MessageChannel: fakeMessageChannel
+      };
+    });
+  });
+
+  describe('in browsers other than Safari', function() {
+    usesMessageChannel(function() {
+      return {
+        navigator: {
+          // Chrome's user agent string contains "Safari" so it's a good test case
+          userAgent:
+            'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36'
+        }
+      };
+    });
+
+    describe('when MessageChannel is unavailable', function() {
+      usesQueueMicrotaskWithSetTimeout(function() {
+        return {
+          navigator: {
+            userAgent: 'CERN-LineMode/2.15 libwww/2.17b3',
+            MessageChannel: undefined
+          }
+        };
+      });
+    });
+  });
+
+  describe('in Node', function() {
+    usesQueueMicrotaskWithoutSetTimeout(function() {
+      return {
+        process: {
+          versions: {
+            node: '3.1415927'
+          }
+        }
+      };
+    });
+  });
+
+  function usesMessageChannel(makeGlobal) {
+    it('uses MessageChannel', function() {
+      const global = {
+        ...makeGlobal(),
+        MessageChannel: fakeMessageChannel
+      };
+      const { clearStack } = privateUnderTest.getStackClearer(global);
+      let called = false;
+
+      clearStack(function() {
+        called = true;
+      });
+
+      expect(called).toBe(true);
+    });
+
+    it('uses setTimeout instead of MessageChannel every 10 calls to make sure we release the CPU', function() {
+      const fakeChannel = fakeMessageChannel();
+      spyOn(fakeChannel.port2, 'postMessage');
+      const setTimeout = jasmine.createSpy('setTimeout');
+      const global = {
+        ...makeGlobal(),
+        setTimeout,
+        MessageChannel: function() {
+          return fakeChannel;
+        }
+      };
+      const { clearStack } = privateUnderTest.getStackClearer(global);
+
+      for (let i = 0; i < 9; i++) {
+        clearStack(function() {});
+      }
+
+      expect(fakeChannel.port2.postMessage).toHaveBeenCalled();
+      expect(setTimeout).not.toHaveBeenCalled();
+
+      clearStack(function() {});
+      expect(fakeChannel.port2.postMessage).toHaveBeenCalledTimes(9);
+      expect(setTimeout).toHaveBeenCalledTimes(1);
+
+      clearStack(function() {});
+      expect(fakeChannel.port2.postMessage).toHaveBeenCalledTimes(10);
+      expect(setTimeout).toHaveBeenCalledTimes(1);
+    });
+
+    it('calls setTimeout when onmessage is called recursively', function() {
+      const setTimeout = jasmine.createSpy('setTimeout');
+      const global = {
+        ...makeGlobal(),
+        setTimeout,
+        MessageChannel: fakeMessageChannel
+      };
+      const { clearStack } = privateUnderTest.getStackClearer(global);
+      const fn = jasmine.createSpy('second clearStack function');
+
+      clearStack(function() {
+        clearStack(fn);
+      });
+
+      expect(fn).not.toHaveBeenCalled();
+      expect(setTimeout).toHaveBeenCalledWith(fn, 0);
+    });
+  }
+
+  function usesQueueMicrotaskWithSetTimeout(makeGlobal) {
+    it('uses queueMicrotask', function() {
+      const global = {
+        ...makeGlobal(),
+        queueMicrotask: function(fn) {
+          fn();
+        }
+      };
+      const { clearStack } = privateUnderTest.getStackClearer(global);
+      let called = false;
+
+      clearStack(function() {
+        called = true;
+      });
+
+      expect(called).toBe(true);
+    });
+
+    it('uses setTimeout instead of queueMicrotask every 10 calls to make sure we release the CPU', function() {
+      const queueMicrotask = jasmine.createSpy('queueMicrotask');
+      const setTimeout = jasmine.createSpy('setTimeout');
+      const global = {
+        ...makeGlobal(),
+        queueMicrotask,
+        setTimeout
+      };
+      const { clearStack } = privateUnderTest.getStackClearer(global);
+
+      for (let i = 0; i < 9; i++) {
+        clearStack(function() {});
+      }
+
+      expect(queueMicrotask).toHaveBeenCalled();
+      expect(setTimeout).not.toHaveBeenCalled();
+
+      clearStack(function() {});
+      expect(queueMicrotask).toHaveBeenCalledTimes(9);
+      expect(setTimeout).toHaveBeenCalledTimes(1);
+
+      clearStack(function() {});
+      expect(queueMicrotask).toHaveBeenCalledTimes(10);
+      expect(setTimeout).toHaveBeenCalledTimes(1);
+    });
+  }
+
+  function usesQueueMicrotaskWithoutSetTimeout(makeGlobal) {
+    it('uses queueMicrotask', function() {
+      const global = {
+        ...makeGlobal(),
+        queueMicrotask: function(fn) {
+          fn();
+        }
+      };
+      const { clearStack } = privateUnderTest.getStackClearer(global);
+      let called = false;
+
+      clearStack(function() {
+        called = true;
+      });
+
+      expect(called).toBe(true);
+    });
+
+    it('does not use setTimeout', function() {
+      const queueMicrotask = jasmine.createSpy('queueMicrotask');
+      const setTimeout = jasmine.createSpy('setTimeout');
+      const global = {
+        ...makeGlobal(),
+        queueMicrotask,
+        setTimeout
+      };
+      const { clearStack } = privateUnderTest.getStackClearer(global);
+
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+
+      expect(queueMicrotask).toHaveBeenCalledTimes(10);
+      expect(setTimeout).not.toHaveBeenCalled();
+    });
+  }
+
+  function fakeMessageChannel() {
+    const channel = {
+      port1: {},
+      port2: {
+        postMessage: function() {
+          channel.port1.onmessage();
+        }
+      }
+    };
+    return channel;
+  }
+});