planning

node_modules/consolidated-events/__tests__/TargetEventHandlers-test.js

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+import TargetEventHandlers from '../src/TargetEventHandlers';
+
+class MockTarget {
+  constructor() {
+    this.addEventListener = jest.fn();
+    this.removeEventListener = jest.fn();
+  }
+}
+
+describe('#add()', () => {
+  it('adds a single event listener to the target the first time', () => {
+    const target = new MockTarget();
+    const eventHandlers = new TargetEventHandlers(target);
+    const listener = () => {};
+    eventHandlers.add('scroll', listener);
+
+    expect(target.addEventListener).toHaveBeenCalledTimes(1);
+    expect(target.addEventListener)
+      .toHaveBeenCalledWith('scroll', jasmine.any(Function), undefined);
+  });
+
+  it('does not add an event listener to the target the second time', () => {
+    const target = new MockTarget();
+    const eventHandlers = new TargetEventHandlers(target);
+    const listener = () => {};
+    const listener2 = () => {};
+    eventHandlers.add('scroll', listener);
+    eventHandlers.add('scroll', listener2);
+
+    expect(target.addEventListener).toHaveBeenCalledTimes(1);
+    expect(target.addEventListener)
+      .toHaveBeenCalledWith('scroll', jasmine.any(Function), undefined);
+  });
+
+  it('adds an event listener for each set of options', () => {
+    const target = new MockTarget();
+    const eventHandlers = new TargetEventHandlers(target);
+    const listener = () => {};
+    const listener2 = () => {};
+    eventHandlers.add('scroll', listener);
+    eventHandlers.add('scroll', listener2, { passive: true });
+
+    expect(target.addEventListener).toHaveBeenCalledTimes(2);
+    expect(target.addEventListener)
+      .toHaveBeenCalledWith('scroll', jasmine.any(Function), undefined);
+    expect(target.addEventListener)
+      .toHaveBeenCalledWith('scroll', jasmine.any(Function), { passive: true });
+  });
+
+  it('adds an event listener for each event type', () => {
+    const target = new MockTarget();
+    const eventHandlers = new TargetEventHandlers(target);
+    const listener = () => {};
+    const listener2 = () => {};
+    eventHandlers.add('scroll', listener);
+    eventHandlers.add('resize', listener2);
+
+    expect(target.addEventListener).toHaveBeenCalledTimes(2);
+    expect(target.addEventListener)
+      .toHaveBeenCalledWith('scroll', jasmine.any(Function), undefined);
+    expect(target.addEventListener)
+      .toHaveBeenCalledWith('resize', jasmine.any(Function), undefined);
+  });
+
+  it('returns an unsubscribe function', () => {
+    const target = new MockTarget();
+    const eventHandlers = new TargetEventHandlers(target);
+    const remove = eventHandlers.add('scroll', () => {});
+
+    expect(typeof remove).toBe('function');
+  });
+
+  it('unsubscribe deletes the event listener when the only handler is removed', () => {
+    const target = new MockTarget();
+    const eventHandlers = new TargetEventHandlers(target);
+    const remove = eventHandlers.add('scroll', () => {});
+    remove();
+
+    expect(target.removeEventListener).toHaveBeenCalledTimes(1);
+    expect(target.removeEventListener)
+      .toHaveBeenCalledWith('scroll', jasmine.any(Function), undefined);
+  });
+
+  it('unsubscribe does not throw when called twice', () => {
+    const target = new MockTarget();
+    const eventHandlers = new TargetEventHandlers(target);
+    const remove = eventHandlers.add('scroll', () => {});
+    remove();
+
+    expect(remove).not.toThrow();
+  });
+
+  it('unsubscribe does not delete the event listener when there are more handlers left', () => {
+    const target = new MockTarget();
+    const eventHandlers = new TargetEventHandlers(target);
+    const remove = eventHandlers.add('scroll', () => {});
+    eventHandlers.add('scroll', () => {});
+    remove();
+
+    expect(target.removeEventListener).toHaveBeenCalledTimes(0);
+  });
+
+  it('unsubscribe called multiple times does not delete the event listener when there are more handlers left', () => {
+    const target = new MockTarget();
+    const eventHandlers = new TargetEventHandlers(target);
+    const remove = eventHandlers.add('scroll', () => {});
+    eventHandlers.add('scroll', () => {});
+    remove();
+    remove();
+
+    expect(target.removeEventListener).toHaveBeenCalledTimes(0);
+  });
+
+  it('unsubscribe deletes the event listener when all handlers are removed', () => {
+    const target = new MockTarget();
+    const eventHandlers = new TargetEventHandlers(target);
+    const remove = eventHandlers.add('scroll', () => {});
+    const remove2 = eventHandlers.add('scroll', () => {});
+    remove();
+    remove2();
+
+    expect(target.removeEventListener).toHaveBeenCalledTimes(1);
+    expect(target.removeEventListener)
+      .toHaveBeenCalledWith('scroll', jasmine.any(Function), undefined);
+  });
+
+  it('unsubscribe handles different options separately', () => {
+    const target = new MockTarget();
+    const eventHandlers = new TargetEventHandlers(target);
+    const remove = eventHandlers.add('scroll', () => {});
+    const remove2 = eventHandlers.add('scroll', () => {}, { passive: true });
+    remove();
+    remove2();
+
+    expect(target.removeEventListener).toHaveBeenCalledTimes(2);
+    expect(target.removeEventListener)
+      .toHaveBeenCalledWith('scroll', jasmine.any(Function), undefined);
+    expect(target.removeEventListener)
+      .toHaveBeenCalledWith('scroll', jasmine.any(Function), { passive: true });
+  });
+});
+
+describe('#handleEvent', () => {
+  it('calls each handler', () => {
+    const target = new MockTarget();
+    const eventHandlers = new TargetEventHandlers(target);
+    const handlers = [jest.fn(), jest.fn(), jest.fn()];
+    handlers.forEach((handler) => {
+      eventHandlers.add('scroll', handler);
+    });
+    const event = {};
+    eventHandlers.handleEvent('scroll', undefined, event);
+
+    handlers.forEach((handler) => {
+      expect(handler).toHaveBeenCalledTimes(1);
+      expect(handler).toHaveBeenCalledWith(event);
+    });
+  });
+
+  it('calls each handler even when one is removed when called', () => {
+    const target = new MockTarget();
+    const eventHandlers = new TargetEventHandlers(target);
+
+    let remove;
+    const firstHandler = jest.fn(() => remove());
+    remove = eventHandlers.add('scroll', firstHandler);
+
+    const secondHandler = jest.fn();
+    eventHandlers.add('scroll', secondHandler);
+
+    const event = {};
+    eventHandlers.handleEvent('scroll', undefined, event);
+
+    expect(firstHandler).toHaveBeenCalledTimes(1);
+    expect(firstHandler).toHaveBeenCalledWith(event);
+
+    expect(secondHandler).toHaveBeenCalledTimes(1);
+    expect(secondHandler).toHaveBeenCalledWith(event);
+  });
+
+  it('calls each handler with options', () => {
+    const target = new MockTarget();
+    const eventHandlers = new TargetEventHandlers(target);
+    const handlers = [jest.fn(), jest.fn(), jest.fn()];
+    handlers.forEach((handler) => {
+      eventHandlers.add('scroll', handler, { passive: true });
+    });
+    const event = {};
+    eventHandlers.handleEvent('scroll', { passive: true }, event);
+
+    handlers.forEach((handler) => {
+      expect(handler).toHaveBeenCalledTimes(1);
+      expect(handler).toHaveBeenCalledWith(event);
+    });
+  });
+});