Add no-unnecessary-qualifier rule

[andy-hanson]

PR checklist

• Addresses an existing issue: Rule request: minimal-namespace-depth #1987
• New feature, bugfix, or enhancement
  • Includes tests
• Documentation update
• Enable CircleCI for your fork (https://circleci.com/add-projects)

What changes did you make?

Added the no-unnecessary-qualifier rule, which warns for A.x if just x would have the same meaning.

[nchen63]

use the one in ruleWalker.ts

[nchen63]

@andy-hanson @adidahiya how about naming this shortest-qualifier?

[andy-hanson]

The rule is about notifying you that a certain node in your AST can be removed if it's unnecessary. It doesn't measure the length of anything.
If you had a rule that warned on !!x (where x is of type boolean), you wouldn't call it shortest-boolean-expression, you'd call it no-unnecessary-bang-bang, right?
Open to name changes, but shortest implies that it compares multiple possible qualifiers for length.

[nchen63]

My concern is that no-unnecessary-qualifier sounds like a binary rule, like either have a qualifier or don't have a qualifier. For example, if you're in the a.b.c namespace, it would only warn if the qualifier exactly matches a.b.c. Maybe it's because I don't view a as a qualifier for b.c (but should?) I don't feel that strongly about changing the name either way.

[andy-hanson]

In my case, I'm just trying to eliminate single qualifiers -- X.foo in namespace X.
But in #1987 there were multiple qualifiers and a few, but not all, could be removed.

I can see how no-unnecessary-qualifier sounds like it does nothing for the latter case. But shortest-qualifier sounds like it does nothing for the former case.

Will think about this later.

[ajafff]

This should work for enum too. At least the name implies that. Don't know if it does already, but there is no test for it.

enum Foo {
    Bar, 
    Baz = Foo.Bar // could be written as Baz = Bar
}

[nchen63]

@andy-hanson thanks! name is ok