stub inquirer's registerPrompt to allow custom prompt modules

Author: mshima

src/adapter.ts

@@ -77,6 +77,7 @@ export class TestAdapter implements InputOutputAdapter {
   promptModule: PromptModule;
   diff: any;
   log: Logger;
+  registerDummyPrompt: (promptName: string, customPromptOptions?: DummyPromptOptions) => PromptModule;
 
   constructor(options: TestAdapterOptions = {}) {
     const { log = createLogger(), ...promptOptions } = options;
@@ -86,15 +87,22 @@ export class TestAdapter implements InputOutputAdapter {
       skipTTYChecks: true,
     });
 
-    for (const promptName of Object.keys(this.promptModule.prompts)) {
-      this.promptModule.registerPrompt(
-        promptName,
+    const actualRegisterPrompt = this.promptModule.registerPrompt.bind(this.promptModule);
+
+    this.registerDummyPrompt = (promptModuleName: string, customPromptOptions?: DummyPromptOptions) =>
+      actualRegisterPrompt(
+        promptModuleName,
         class CustomDummyPrompt extends DummyPrompt {
           constructor(question: PromptQuestion, rl: any, answers: PromptAnswers) {
-            super(question, rl, answers, promptOptions);
+            super(question, rl, answers, customPromptOptions ?? promptOptions);
           }
         } as any,
       );
+
+    this.promptModule.registerPrompt = (name: string) => this.registerDummyPrompt(name);
+
+    for (const promptName of Object.keys(this.promptModule.prompts)) {
+      this.promptModule.registerPrompt(promptName, undefined as any);
     }
 
     this.diff = sinonSpy();

src/helpers.ts

@@ -115,17 +115,11 @@ export class YeomanTest {
       throw new Error('environment is not an Environment instance');
     }
 
-    const { promptModule } = environment.adapter as TestAdapter;
+    const testAdapter = environment.adapter as TestAdapter;
+    const { promptModule } = testAdapter;
 
     for (const name of Object.keys(promptModule.prompts)) {
-      promptModule.registerPrompt(
-        name,
-        class CustomDummyPrompt extends DummyPrompt {
-          constructor(question: PromptQuestion, rl: any, answers: PromptAnswers) {
-            super(question, rl, answers, { ...options, mockedAnswers });
-          }
-        } as any,
-      );
+      testAdapter.registerDummyPrompt(name, { ...options, mockedAnswers });
     }
   }