BeAssignableToTypeOf fails with confusing error when just one of actual or expected is nil

[nwmahoney]

The relevant lines of code are here.

Our code under test:

func Configure() interface{} {
  return nil
}

Our test:

It("returns a govmomi client", func() {
  expectedClient := new(govmomi.Client)

  actualClient := packageundertest.Configure()
  Expect(actualClient).To(BeAssignableToTypeOf(expectedClient))
})

Test output:

    returns a govmomi client [It]
    /Users/pivotal/go/src/github.com/rowanjacobs/terraform-provider-vsphereovf/vsphereovf/provider_test.go:68

    Refusing to compare <nil> to <nil>.
    Be explicit and use BeNil() instead.  This is to avoid mistakes where both sides of an assertion are erroneously
 uninitialized.

This confuses us since expectedClient is not actually nil (printing it and its address confirms this).

[williammartin]

I think this is a mistake in the BeAssignableToTypeOf matcher. We can see here:

gomega/matchers/assignable_to_type_of_matcher.go

Line 15 in 11025fe

if actual == nil || matcher.Expected == nil {

that we are doing an Or comparison but in the EqualTo matcher here:

gomega/matchers/equal_matcher.go

Line 15 in 11025fe

if actual == nil && matcher.Expected == nil {

we are doing an And comparison.

I don't see why they would be different (but I haven't delved super deeply into the BeAssignableToTypeOf matcher).

Would you be ok opening a PR? Otherwise might get round to it tomorrow or monday.

[rowanjacobs]

Sure, we'll open a PR for it.