Detect and block Exercism stub throw in two-fer analyzer

Author: samirhssn

src/analyzers/practice/two-fer/index.ts

@@ -101,6 +101,7 @@ export class TwoFerAnalyzer extends AnalyzerImpl {
 
     if (hasStubThrow(this.mainMethod)) {
       this.disapprove(REMOVE_STUB_THROW())
+      return
     }
 
     // Now we want to ensure that the method signature is sane and that it has

src/comments/remove_stub_throw.ts

@@ -2,4 +2,4 @@ import { factory, CommentType } from '~src/comments/comment'
 
 export const REMOVE_STUB_THROW = factory`
 Remove this placeholder throw statement. It is dead code.
-`('javascript.general.remove_stub_throw', CommentType.Actionable)
+`('javascript.general.remove_stub_throw', CommentType.Essential)

test/analyzers/two-fer/stub-throw.ts

@@ -0,0 +1,43 @@
+import { TwoFerAnalyzer } from '~src/analyzers/practice/two-fer'
+import { makeAnalyze } from '~test/helpers/smoke'
+
+const analyze = makeAnalyze(() => new TwoFerAnalyzer())
+
+describe('two-fer stub throw detection', () => {
+  it('blocks canonical exercism stub throw', async () => {
+    const solution = `
+      export function twoFer(name = 'you') {
+        return 'One for you, one for me.'
+        throw new Error('Remove this line and implement the function');
+      }
+    `.trim()
+
+    const output = await analyze(solution)
+
+    const stub = output.comments.find(
+      (c) => c.externalTemplate === 'javascript.general.remove_stub_throw'
+    )
+
+    expect(stub).toBeDefined()
+    expect(stub?.type).toBe('essential')
+  })
+
+  it('does not block normal error throws', async () => {
+    const solution = `
+      export function twoFer(name = 'you') {
+        if (name === 'bad') {
+          throw new Error('Invalid name');
+        }
+        return \`One for \${name}, one for me.\`
+      }
+    `.trim()
+
+    const output = await analyze(solution)
+
+    const stub = output.comments.find(
+      (c) => c.externalTemplate === 'javascript.general.remove_stub_throw'
+    )
+
+    expect(stub).toBeUndefined()
+  })
+})