Problem

Given the following two files in a package:

file1.go:

package foo

import (
    bar "some.repo/import/bar"
)

type Barrier interface {
    Baz(bar.Qux)
}

...

file2.go:

package foo

import (
    _ "some.repo/import/bar"
)

...

, suppose you want to generate a mock of Barrier.

Today, running moq -out barrier.mock.go . Barrier would produce the following:

barrier.mock.go

package foo

import (
    _ "some.repo/import/bar"
    "sync"
)

...

type BarrierMock struct {
    // BazFunc mocks the Baz method.
    BazFunc(quxer _.Qux)

...

, which is invalid Go 😢 .

Why

This is caused by a specific interaction between two steps:

• When parsing the import statements of each file in the requested package to construct the alias map, they are processed in alphabetical filename order.
• When adding an alias to a map, it overwrites any existing alias for that import path.

Combined, the above means the valid bar alias is overwritten by the invalid _ that gets processed later, and applied to the imported types in the generated functions.

Solution

Ignore anonymous imports when constructing the alias map. This means a valid alias will never be overwritten, and as anonymous imports will always be unused by a mock, they will always be safe to ignore.