1 files changed, 38 insertions, 0 deletions
diff --git a/spec/ruby/core/module/module_exec_spec.rb b/spec/ruby/core/module/module_exec_spec.rb
new file mode 100644
index 0000000000..6b36e8a02f
--- /dev/null
+++ b/spec/ruby/core/module/module_exec_spec.rb
@@ -0,0 +1,38 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Module#module_exec" do
+  it "does not add defined methods to other classes" do
+    FalseClass.module_exec do
+      def foo
+        'foo'
+      end
+    end
+    -> {42.foo}.should.raise(NoMethodError)
+  end
+
+  it "defines method in the receiver's scope" do
+    ModuleSpecs::Subclass.module_exec { def foo; end }
+    ModuleSpecs::Subclass.new.respond_to?(:foo).should == true
+  end
+
+  it "evaluates a given block in the context of self" do
+    ModuleSpecs::Subclass.module_exec { self }.should == ModuleSpecs::Subclass
+    ModuleSpecs::Subclass.new.module_exec { 1 + 1 }.should == 2
+  end
+
+  it "raises a LocalJumpError when no block is given" do
+    -> { ModuleSpecs::Subclass.module_exec }.should.raise(LocalJumpError)
+  end
+
+  it "passes arguments to the block" do
+    a = ModuleSpecs::Subclass
+    a.module_exec(1) { |b| b }.should.equal?(1)
+  end
+
+  describe "with optional argument" do
+    it "does not destructure a single array argument" do
+      ModuleSpecs::Subclass.module_exec([1, 2, 3]) { |a = 99| a }.should == [1, 2, 3]
+    end
+  end
+end