Mock.IsMethodCallable implements its own incomplete expected argument checking. So it doesn't always work. It should be using the same methods as Mock.Called to check if it is callable.

It also has no reason to accept a TestingT, it doesn't use it at all, there is no point calling Helper, which also isn't part of TestingT.

I also see no sensible use case for IsMethodCallable.

Description

If the expected Args of a Call in Mock.ExpectedCalls are dynamic (mock.Anything, mock.MatchedBy, etc...) then Mock.IsMethodCallable will return the wrong answer.

Step To Reproduce

package kata_test

import (
	"testing"

	"github.com/stretchr/testify/mock"
	"github.com/stretchr/testify/require"
)

type MyMock struct {
	mock.Mock
}

func TestEventuallyFast(t *testing.T) {
	m := &MyMock{}
	m.On("MyMethod", 1).Return()
	m.On("MyMethod", mock.Anything).Return()
	require.True(t, m.IsMethodCallable(t, "MyMethod", 1))
	require.True(t, m.IsMethodCallable(t, "MyMethod", 2))
}

Expected behavior

Testcase passes

Actual behavior

m.IsMethodCallable(t, "MyMethod", 2) incorrectly returns false.