Support Embedded Interfaces

[kevinbirch]

This PR inlines methods from embedded interfaces into the generated Fake. It does this by resolving embeded field identifers from the model cache and prepending the nested methods in source order. This recursive expansion happens just before the template is rendered so that the definition of embedded interfaces can occur after the definition of the embedder. To resolve embedded intefaces not defined in the current package, all intefaces in all imported packages are also scanned.

The -file flag has been removed because we always want to scan an entire package. This ensure that we can find all available interfaces that might be embedded.

Support for map and function parameter types has also been added.

[solumos]

Will this break for an embedded interface that's imported from another package that embeds another interface from another package? I think so, if main doesn't import bar directly.

e.g.

package main

import (
	"foo"
)

// Interface to mock
type Embedder interface {
	foo.DoubleEmbedder
	Other(string) string
}

package foo

import (
	"bar"
)

type DoubleEmbedder interface {
        bar.Breaker
}

package bar

type Breaker interface {
        Break()
}

[solumos]

To resolve embedded intefaces not defined in the current package, all interfaces in all imported packages are also scanned.

More precisely - are packages imported by imported packages scanned if they're not imported in the current package?

[kevinbirch]

Yes it will break, very perceptive. I decided that the trouble required to fully recursively resolve a hierarchy like that wouldn't be worth the trouble (for now anyway).

are packages imported by imported packages scanned if they're not imported in the current package?

nope, they're not

[kevinbirch]

It seems unlikely that such a case would come up very often. If it does then we can support it. Just the automatic resolution of imports puts this package far ahead of similar ones.

[solumos]

the trouble required to fully recursively resolve a hierarchy like that wouldn't be worth the trouble (for now anyway)

Cool, I agree