Ts-morph: Calling `.remove()` removes comment which shouldn't be removed

[donaldpipowitch]

Hi there! This is my first try to use ts-simple-ast. We would like to convert certain interfaces to types. But in some cases "trailing" comments are removed and we don't know why.

Given the following example:

{
  "name": "ts-ast-test",
  "version": "1.0.0",
  "private": true,
  "scripts": {
    "start": "ts-node index.ts"
  },
  "dependencies": {
    "ts-simple-ast": "^11.2.1"
  },
  "devDependencies": {
    "ts-node": "^6.0.5"
  }
}

import Project, { TypeAliasDeclarationStructure } from 'ts-simple-ast';

const project = new Project();
const example = `interface Foo {
  foo: string;
}

// foo
const foo = 1;`;
const file = project.createSourceFile('example.ts', example);
const interfaces = file.getInterfaces();

interfaces.forEach((myInterface) => {
  const typeAlias: TypeAliasDeclarationStructure = {
    name: myInterface.getName(),
    type:
      '{' +
        myInterface.getMembers().map(p => p.getText()).join(' ') +
      '}'
  };
  file.insertTypeAlias(myInterface.getChildIndex(), typeAlias);
  myInterface.remove();
});
console.log(file.getText());

The output is this:

type Foo = {foo: string;};
const foo = 1;

As you can see the comment // foo was removed. I wonder why? When I paste the same example to https://astexplorer.net/ with TypeScript selected as the parser it shows that the comment is not a trailing comment of interface Foo, but a leading comment to const foo = 1;.

So is this a bug that the comment will be removed when myInterface.remove(); is called?

Thank you.

[dsherret]

Hi @donaldpipowitch, yes this is a bug and thanks for reporting this! That comment is not owned by the interface. In the beginning of this library comments were an afterthought so there are still a few areas like this that aren't correct.

[cancerberoSgx]

@dsherret - just in case, this is the difference between ts.Node getText vs getFullText - and the same for other methods like getStart() getFullStart() getFullWidth(), etc - if internally the library use "Full" methods instead of non full then those trailing comments (tribia content as they call it) will be considered. - if not it will be discarded. My two cents.

[dsherret]

@cancerberoSgx thanks, but no it's not related to that. I fixed a similar issue to this before so I'll have this fixed soon.

[dsherret]

Fixed in 11.2.2. Let me know if you run into any other issues.

[donaldpipowitch]

This is awesome. I'll test it. Thank you _very_ much for the quick fix and the release.