doc(testing): add section on ignoring dependencies

This describes a new feature of aurelia-testing introduced by
aurelia/testing#89

current/en-us/9. testing/1. components.md

@@ -308,6 +308,55 @@ describe('MyAttribute', () => {
 
 Now the service dependency for `MyComponent` will be resolved through DI automatically.
 
+## Ignoring dependencies
+
+You might want to test a component that is composed of subcomponents with possible side-effects that you don't want to encounter during your test. In that case, you can prevent specific resources from being loaded during the test by calling `ignoreDependencies()`. This will prevent a module `<require>`d by a template
+from actually being loaded.
+
+```HTML A composed component - template
+<template>
+  <require from="my-component"></require>
+
+  <my-component first-name="Alice"></my-component>
+
+  ${message}
+</template>
+```
+
+```JavaScript A composed component - View Model
+class MyParent {
+  message = "Hello from the parent!"
+}
+```
+
+```JavaScript Ignoring specific resources when loading a component for testing
+import {StageComponent} from 'aurelia-testing';
+import {bootstrap} from 'aurelia-bootstrapper';
+
+describe('MyParentComponent', () => {
+  let component;
+
+  beforeEach(() => {
+    component = StageComponent
+      .withResources('src/my-parent-component')
+      .inView('<my-composed-component></my-parent-component>')
+      .ignoreDependencies("my-component");
+  });
+
+  it("doesn't load the subcomponent", done => {
+    component.create(bootstrap).then(() => {
+      expect(component.element.textContent.trim()).toEqual("Hello from the parent!");
+
+      done();
+    });
+  });
+
+  afterEach(() => {
+    component.dispose();
+  });
+});
+```
+
 ## Improving Readability with Multi-line Strings
 
 You can improve the readability of your complex views by using template literals in your tests -