Add no_args support for stubs

Fixes https://github.com/icy-arctic-fox/spectator/issues/28

CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+### Added
+- Added support for `with(no_args)` for method stubs. [#28](https://github.com/icy-arctic-fox/spectator/issues/28)
+
 ## [0.9.38] - 2021-05-27
 ### Fixed
 - Fix `Channel::ClosedError` when using default Crystal Logger. [#27](https://github.com/icy-arctic-fox/spectator/issues/27)

spec/issues/github_issue_28_spec.cr

@@ -0,0 +1,19 @@
+require "../spec_helper"
+
+Spectator.describe "GitHub Issue #28" do
+  class Test
+    def foo
+      42
+    end
+  end
+
+  mock Test do
+    stub foo
+  end
+
+  it "matches method stubs with no_args" do
+    test = Test.new
+    expect(test).to receive(:foo).with(no_args).and_return(42)
+    test.foo
+  end
+end

src/spectator/dsl/mocks.cr

@@ -170,4 +170,8 @@ module Spectator::DSL
     {% end %}
     %stubs
   end
+
+  def no_args
+    ::Spectator::Mocks::NoArguments.new
+  end
 end

src/spectator/mocks/no_arguments.cr

@@ -0,0 +1,21 @@
+require "./arguments"
+
+module Spectator::Mocks
+  class NoArguments < Arguments
+    def args
+      Tuple.new
+    end
+
+    def opts
+      NamedTuple.new
+    end
+
+    def ===(other : Arguments) : Bool
+      other.args.empty? && other.opts.empty?
+    end
+
+    def ===(other) : Bool
+      false
+    end
+  end
+end