Added additional documentation to the software templating section including unit tests.

Signed-off-by: Steven Billington <sbillington@aurorasolar.com>

docs/features/software-templates/writing-templates.md

@@ -734,7 +734,7 @@ an entity reference, such as the `kind`, `namespace`, and `name`.
 
 ### pick
 
-This `pick` filter allows you to select specific properties from an object.
+This `pick` filter allows you to select specific properties (`kind`, `namespace`, `name`) from an object.
 
 **Usage Example**
 

docs/features/software-templates/writing-tests-for-actions.md

@@ -4,15 +4,13 @@ title: Writing Tests For Actions
 description: How to write tests for actions
 ---
 
-Once you created a new action, your own custom one, or you would like to contribute new actions, you have to cover it with
-Unit tests to be sure that your actions do what they suppose to do.
+# Unit Testing Custom Actions
 
-Make sure that you cover the most of scenario's, which could happen with the action.
-One of indispensable part of the test is to supply the context to a handler of action for the execution.
-We encourage you to use a utility method for that, so your tests are immune to structural changes of context.
-What is inevitably going to happen during the time.
+Unit tests help prevent regressions in custom action functionality. The `createTemplateAction` function that is the core of a custom action can be difficult to mock. There are helper methods that can assist.
 
-Example how to use it:
+## Mocking the Context
+
+The `handler` property of the `createTemplateAction` input object expects a context. You can create a mock context using the code below:
 
 ```typescript
 import { createMockActionContext } from '@backstage/plugin-scaffolder-node-test-utils';
@@ -29,10 +27,11 @@ expect(mockContext.output).toHaveBeenCalledWith(
 );
 ```
 
+### Mocking a Workspace within the Context object
+
 One thing to be aware about: if you would like to call `createMockActionContext` inside `it`,
 you have to provide a `workspacePath`. By default, `createMockActionContext` uses
-`import { createMockDirectory } from '@backstage/backend-test-utils';` to create it for you.
-This implementation contains a hook inside which creates this limitation. So in this case you can do then:
+`import { createMockDirectory } from '@backstage/backend-test-utils';` to create it for you. You can use the code below to customize the `workspacePath` without using the default workspace of the `createMockActionContext` function.
 
 ```typescript
 describe('github:autolinks:create', async () => {
@@ -55,3 +54,63 @@ describe('github:autolinks:create', async () => {
   });
 });
 ```
+
+## Mocking a Config Core Service
+
+If your custom Action requires the Config Core Service within execution of the `handler(ctx)` such as the custom action below, mocking the context object can be done by building a `mockContext` with the `ConfigReader` function within the `@backstage/config` package.
+
+```typescript
+// custom-action.ts
+import { Config } from '@backstage/config';
+
+export const customActionRequiringConfigCoreService = (config: Config) => {
+  const fieldRequiringValueFromConfig = config.getString('app.service.url');
+  return createTemplateAction({
+    ...
+    async handler(ctx) {
+      // Some code requiring the config const
+      ctx.logger.info(fieldRequiringValueFromConfig);
+    }
+  })
+}
+```
+
+```typescript
+// custom-action.test.ts
+import { ConfigReader } from '@backstage/config';
+import { customActionRequiringConfigCoreService } from './custom-action.ts';
+...
+const mockConfig = new ConfigReader({
+  app: {
+    service: {
+      url: 'https://api.service.io/graphql',
+      apiKeyId: '123',
+      apiKeySecret: '123abc',
+    },
+  },
+});
+...
+const action = customActionRequiringConfigCoreService(mockConfig);
+await action.handler({
+  ...mockContext
+})
+```
+
+## Mocking a Cache Core Service
+
+Similar to the `Mocking a Config Core Service` section above, if your custom action expects a Cache Core Service Object as part of the function input, you can mock it out with the following:
+
+```typescript
+import { CacheService } from '@backstage/backend-plugin-api';
+
+const mockCacheServiceMethods = {
+  get: jest.fn(),
+  set: jest.fn(),
+  delete: jest.fn(),
+};
+
+const mockCacheService = mockCacheServiceMethods as unknown as CacheService;
+
+const action = customActionRequiringCacheCoreService(mockCacheService);
+...
+```