Always remove self_package import

[linzhp]

When users provide -self_package, gomock should always exclude that import from generated mock. The pkg.Name can be incorrectly determined in reflect mode:

mock/mockgen/reflect.go

Lines 206 to 211 in 0b73a1d

	pkg := &model.Package{
	// NOTE: This behaves contrary to documented behaviour if the
	// package name is not the final component of the import path.
	// The reflect package doesn't expose the package name, though.
	Name: path.Base({{printf "%q" .ImportPath}}),
	}

We should not reset outputPackagePath when it is passed from -self_package.

Fixing #342

[codyoss]

Not sure why this is working on CI, but if you run go install ./... && ./ci/check_go_generate.sh locally this fails.

cc @cvgw @nguyenfilip Something we should look into

[codyoss]

This may having nothing to do with this PR btw, but would like to get it fixed before evaluating further PRs.

[codyoss]

@linzhp thanks for your patience. I wanted to make sure we got our build properly working on master before we accepted any more PRs. Would you mind rebasing this as there are now some conflicts.

[linzhp]

@codyoss rebased

[linzhp]

Are you planning another release soon? It's been 8 months

[codyoss]

Yes, originally planned for tomorrow: https://github.com/golang/mock/milestone/1
Should land sometime this week. This package recently switched maintainers, so there was a bit of a lull.

[codyoss]

@linzhp One more thing, would you mind adding a testcase under mockgen/internal/tests. All it would need to be is a source file with a go: generate directive and the generated code. Our ci will try to regenerate all these and check for diffs to make sure this does not break again in the future.

[linzhp]

@codyoss Added a test case

[codyoss]

@linzhp Thank you for your patience and contribution! Should have this rolled up in a release later this week 🎆