add lint use_string_in_part_of_directives

[a14n]

Description

From effective dart:

DO use strings in part of directives.

BAD:

part of my_library;

GOOD:

part of '../../my_library.dart';

Fixes dart-lang/sdk#58777

[coveralls]

Coverage decreased (-0.08%) to 95.663% when pulling 2051f94 on a14n:use_string_in_part_of_directives into 7d51bf6 on dart-lang:main.

[pq]

Would you consider migrating this test to the reflective_test_loader style? These run faster and are easier to debug.

FWIW ConditionalUriDoesNotExistTest and PreferConstConstructorsTest are examples of tests that uses this style for tests that require multiple files.

(Aside: we should really write up some docs for this... 😬 )

[a14n]

For this rule I need several files. I don't find example dealing with multiple files. Do you have an example of such case?

[pq]

Sure!

In this case newFile2 creates a.dart which is imported by the test file in assertNoDiagnostics.

  test_deferred_arg() async {
    newFile2('$testPackageLibPath/a.dart', '''
class A {
  const A();
}

const aa = A();
''');

    await assertNoDiagnostics(r'''
import 'a.dart' deferred as a;

class B {
  const B(Object a);
}

main() {
  var b = B(a.aa);
  print(b);
}   
''');
  }

You can call newFile2 multiple times with different library names ($testPackageLibPath/b.dart etc.) to get more libraries to import into your test file if needed.

I need to run out for a but but if you get stuck, feel free to share how far you get and I'm happy to take a look.

Thanks!

[a14n]

Thanks for your help. Tests are now migrated. PTAL

[pq]

Super. Thanks!