Patching module specific functions

[omus]

Noticed when looking into #14. Mocking doesn't work if the user wants to mock a function from a specific module, Requests.get vs get.

using Mocking
Mocking.enable()

using Base.Test
import Requests
import HttpCommon

function foo(status::Int64)
    Requests.statuscode(@mock Requests.get("http://httpbin.org/status/$status"))
end

patch = @patch Requests.get(x::String) = HttpCommon.Response(200, Dict{AbstractString, AbstractString}(), UInt8[])

apply(patch) do
    @test foo(200) == 200
end

Additionally a user may accidently do the following and get get a "no method matching" exception for ismocked.

using Mocking
Mocking.enable()

using Base.Test
import Requests
import Requests: get
import HttpCommon

function foo(status::Int64)
    Requests.statuscode(@mock Requests.get("http://httpbin.org/status/$status"))
end

# Changed from Requests.get to just get
patch = @patch get(x::String) = HttpCommon.Response(200, Dict{AbstractString, AbstractString}(), UInt8[])

apply(patch) do
    @test foo(200) == 200
end

[oxinabox]

This is pretty annoying.
I can take a crack at it at some point.

I think an unobtrusive change would be to name mangle
Foo.bar into Foo_MOCKDOT_bar
and create a local function of that name.
(Maybe use a UUID instead of MOCKDOT to reduce chance of clash -- at the cost of worse stack traces)

But other options exist.
Maybe something value rather than name based.

[omus]

Fixed by #63