Adds AnythingOfTypeT wrapper function

[chrsalx]

Summary

Adds AnythingOfTypeT function as a wrapper that provides generics support to AnythingOfType.

Changes

• bumps go.mod version to 1.19.
• Adds AnythingOfTypeT function.
• Adds tests for AnythingOfTypeT.

Motivation

The AnythingOfType function allows us to configure mocking behavior for any value for the provided type. The caveat to this is that AnythingOfType expects a string, this requires the user to know beforehand the full name of the type as it will be defined by Go at runtime.

This can lead to issues during the development of the tests caused by typos or by not naming the desired type properly.

Using generics, Go can provide the name of the type without breaking the existing API.

c := mockedService.
	On("TestMethod", AnythingOfTypeT[int]()).
	Return(nil)

assert.Nil(t, c.TestMethod(5))

[dolmen]

The testify module doesn't yet rely on a Go version that has generics. testify is now a major point in the Go ecosystem, so it would not be wise yet to block users from upgrading testify (to benefit from bug fixes) if they are not able to upgrade their Go toolchain (example: support of a GOOS or GOARCH being removed in recent versions).

So that new code that use generics must be put in a separate file mock_generics.go with a //go:build go1.18 guard.

[dolmen]

We have mock.IsType: this is the function that should have a generic version. So prefix should be IsType, not AnythingOfType.

[dolmen]

See also #1442.