(#443) testing: log eventBusMock subscriber errors by default

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Last Changes
 
+- [#443](https://github.com/LaxarJS/laxar/issues/443): testing: initialize eventBusMock with noisy error log
 - [#448](https://github.com/LaxarJS/laxar/issues/448): documentation: fixed markdown indent in API index
 
 

docs/api/testing.event_bus_mock.md

@@ -33,7 +33,7 @@ published events.
 | -------- | ---- | ----------- |
 | _options_ | `Object` |  additional options |
 | _options.nextTick_ | `Object` |  an alternative callback for scheduling the next event bus cycle (such as window.setTimeout) |
-| _options.errorHandler_ | `Object` |  an alternative error handler, e.g. to inspect error conditions during test |
+| _options.errorHandler_ | `Object` |  an alternative error handler, e.g. to inspect error conditions during test. By default, exceptions thrown by subscribers to the mock will be reported using `window.console.error` |
 
 ##### Returns
 

lib/testing/event_bus_mock.js

@@ -29,7 +29,8 @@ import { create as createLogMock } from './log_mock';
  * @param {Object} [options.nextTick]
  *    an alternative callback for scheduling the next event bus cycle (such as window.setTimeout)
  * @param {Object} [options.errorHandler]
- *    an alternative error handler, e.g. to inspect error conditions during test
+ *    an alternative error handler, e.g. to inspect error conditions during test. By default, exceptions
+ *    thrown by subscribers to the mock will be reported using `window.console.error`
  *
  * @return {EventBusMock}
  *    a fresh mock instance
@@ -57,7 +58,11 @@ export function create( { nextTick, errorHandler } = {} ) {
       createLogMock(),
       nextTick || fallbackTick,
       setTimeout,
-      errorHandler
+      errorHandler || (( ...args ) => {
+         if( window.console && window.console.error ) {
+            window.console.error( ...args );
+         }
+      })
    );
 
    /**

lib/testing/spec/event_bus_mock_spec.js

@@ -65,6 +65,23 @@ describe( 'An eventBus mock', () => {
 
    ///////////////////////////////////////////////////////////////////////////////////////////////////////////
 
+   it( 'reports subscriber errors to console.error by default', () => {
+      spyOn( window.console, 'error' );
+      eventBusMock = createEventBusMock();
+      let e;
+      eventBusMock.subscribe( 'myEvent', () => {
+         e = new Error( 'error' );
+         throw e;
+      } );
+      eventBusMock.publish( 'myEvent' );
+      eventBusMock.flush();
+
+      expect( window.console.error ).toHaveBeenCalledWith( jasmine.any( String ), jasmine.any( Object ) );
+      expect( window.console.error.calls.mostRecent().args[ 1 ][ 'Exception' ] ).toEqual( e );
+   } );
+
+   ///////////////////////////////////////////////////////////////////////////////////////////////////////////
+
    it( 'allows to synchronously flush pending events', () => {
       const spyA = jasmine.createSpy( 'A' );
       const spyB = jasmine.createSpy( 'B' );