Implement interface helper does not consider what is already implemented on base classes

[Tyriar]

TypeScript Version: 2.6.1 (VS Code Insiders)

Code

interface MyInterface {
  foo(): void;
}

interface IBase extends MyInterface {
  bar(): void;
}

abstract class Base implements MyInterface {
  foo(): void {}
}

class MyClass extends Base implements IBase {

}

When I implement interface IBase, it's not figuring out which methods are already implemented on the base classes.

Expected behavior:

class MyClass extends Base implements IBase {
  bar(): void {
    throw new Error("Method not implemented.");
  }
}

Actual behavior:

class MyClass extends Base implements IBase {
  bar(): void {
    throw new Error("Method not implemented.");
  }
  foo(): void {
    throw new Error("Method not implemented.");
  }

}

[mhegazy]

PRs welcomed...

[MhdTlb]

I would like to work on this issue but I need some guidance

[mhegazy]

sure. The code for this fix is in https://github.com/Microsoft/TypeScript/blob/master/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts

The fix should probably be in https://github.com/Microsoft/TypeScript/blob/d998e97d8c64acf1ed4b8cd508a4589c110bd3aa/src/services/codefixes/helpers.ts#L36 to change const classMembers = classDeclaration.symbol.members; to const classMembers = checker.getPropertiesOfType(checker.getTypeAtLocation(classDeclaration));

[shobhitchittora]

@mhegazy I've made the required changes and would like to test now. How can I test whether the issue is fixed? Also how to debug ts compiler changes?

PS: I used vscode to reproduce the issue.

[mhegazy]

VSCode ships with an older version of TypeScript. Please see Using Newer TypeScript Versions documentation for more details on updating your VSCode to use a different version of TypeScript.

[mhegazy]

u also should write a unit test for it, see https://github.com/Microsoft/TypeScript/blob/master/tests/cases/fourslash/codeFixClassImplementInterfaceProperty.ts

[shobhitchittora]

@mhegazy @Tyriar Need help debugging ts executions from vscode. I tried putting a debugger; in my ts file hoping that it'd stop while fixing incorrectly implemented interfaces in my vscode OSSDEV build, but it does not.

Thanks in advance.
PS: I've configured my vscode nightly build (from master) to load local tsserver.js.

[Tyriar]

@mjbvz might be able to help with debugging in vscode