Error when setting base test providers into several unit tests - unit-testing

Question

I use Angular2 RC1 and I have several unit tests regarding different components with the following structure:
import {provide} from '#angular/core';
import {
TestComponentBuilder
} from '#angular/compiler/testing';
import {
beforeEach,
ddescribe,
xdescribe,
describe,
expect,
iit,
inject,
injectAsync,
async,
beforeEachProviders,
setBaseTestProviders,
it,
xit
} from '#angular/core/testing';
import {
TEST_BROWSER_DYNAMIC_PLATFORM_PROVIDERS,
TEST_BROWSER_DYNAMIC_APPLICATION_PROVIDERS
} from '#angular/platform-browser-dynamic/testing/browser';
describe('Test component 1', () => {
setBaseTestProviders(TEST_BROWSER_DYNAMIC_PLATFORM_PROVIDERS,
TEST_BROWSER_DYNAMIC_APPLICATION_PROVIDERS);
it('should something',
async(inject([TestComponentBuilder], (tcb: TestComponentBuilder) => {
var updateService = new UpdateService();
tcb.overrideProviders(ShapeCircleLayerComponent, [
provide(UpdateService, { useValue: updateService })
])
.createAsync(Component1).then((componentFixture) => {
(...)
});
});
});
});
Each test works if run alone but when I run them at the same time within Karma, I get the following error:
Chrome 50.0.2661 (Linux 0.0.0) Test for shape circle layer encountered a declaration exception FAILED
Error: Cannot set /home/(...)/my-project providers because it has already been called
at new BaseException (/home/(...)/my-project/node_modules/#angular/core/src/facade/exceptions.js:17:23)
at Object.setBaseTestProviders (/home/(...)/my-project/node_modules/#angular/core/testing/test_injector.js:74:15)
```
It seems that several tests that set base test providers (TEST_BROWSER_DYNAMIC_PLATFORM_PROVIDERS,
TEST_BROWSER_DYNAMIC_APPLICATION_PROVIDERS) can't be executed at the same time.
Does anyone have this problem? Thanks very much!

Answer 1

As #teleaziz suggested, you should do this only once. So such processing needs to be moved into the karma-test-shim.js file. Here is a sample:
System.import('#angular/platform-browser/src/browser/browser_adapter')
.then(function(browser_adapter) { browser_adapter.BrowserDomAdapter.makeCurrent(); })
.then(function() {
return Promise.all([
System.import('#angular/core/testing'),
System.import('#angular/platform-browser-dynamic/testing/browser')
]);
})
.then(function(modules) {
var testing = modules[0];
var testingBrowser = modules[1];
testing.setBaseTestProviders(
testingBrowser.TEST_BROWSER_DYNAMIC_PLATFORM_PROVIDERS,
testingBrowser.TEST_BROWSER_DYNAMIC_APPLICATION_PROVIDERS);
})
.then(function() { return Promise.all(resolveTestFiles()); })
.then(function() { __karma__.start(); }, function(error) { __karma__.error(error.stack || error); });