Merge pull request #153 from waterlink/feature/152/recognize_module_as_class_contract

Recognize module as a class contract

Author: egonSchiele

Diff for: lib/contracts.rb

@@ -249,7 +249,7 @@ def self.make_validator(contract)
       # e.g. Fixnum, Num
       if contract.respond_to? :valid?
         lambda { |arg| contract.valid?(arg) }
-      elsif klass == Class
+      elsif klass == Class || klass == Module
         lambda { |arg| arg.is_a?(contract) }
       else
         lambda { |arg| contract == arg }

Diff for: spec/contracts_spec.rb

@@ -567,6 +567,38 @@ def self.greeting(name)
     end
   end
 
+  describe "module contracts" do
+    it "passes for instance of class including module" do
+      expect(
+        ModuleContractExample.hello(ModuleContractExample::AClassWithModule.new)
+      ).to eq(:world)
+    end
+
+    it "passes for instance of class including inherited module" do
+      expect(
+        ModuleContractExample.hello(ModuleContractExample::AClassWithInheritedModule.new)
+      ).to eq(:world)
+    end
+
+    it "does not pass for instance of class not including module" do
+      expect do
+        ModuleContractExample.hello(ModuleContractExample::AClassWithoutModule.new)
+      end.to raise_error(ContractError, /Expected: ModuleContractExample::AModule/)
+    end
+
+    it "does not pass for instance of class including another module" do
+      expect do
+        ModuleContractExample.hello(ModuleContractExample::AClassWithAnotherModule.new)
+      end.to raise_error(ContractError, /Expected: ModuleContractExample::AModule/)
+    end
+
+    it "passes for instance of class including both modules" do
+      expect(
+        ModuleContractExample.hello(ModuleContractExample::AClassWithBothModules.new)
+      ).to eq(:world)
+    end
+  end
+
   describe "Contracts to_s formatting in expected" do
     def not_s(match)
       Regexp.new "[^\"\']#{match}[^\"\']"

Diff for: spec/fixtures/fixtures.rb

@@ -588,3 +588,42 @@ def something(a, b)
     nil
   end
 end
+
+module ModuleContractExample
+  include Contracts
+
+  module AModule
+  end
+
+  module AnotherModule
+  end
+
+  module InheritedModule
+    include AModule
+  end
+
+  class AClassWithModule
+    include AModule
+  end
+
+  class AClassWithoutModule
+  end
+
+  class AClassWithAnotherModule
+    include AnotherModule
+  end
+
+  class AClassWithInheritedModule
+    include InheritedModule
+  end
+
+  class AClassWithBothModules
+    include AModule
+    include AnotherModule
+  end
+
+  Contract AModule => Symbol
+  def self.hello(thing)
+    :world
+  end
+end