1 files changed, 41 insertions, 0 deletions
diff --git a/spec/rubyspec/core/kernel/instance_variable_defined_spec.rb b/spec/rubyspec/core/kernel/instance_variable_defined_spec.rb
new file mode 100644
index 0000000000..969d36c731
--- /dev/null
+++ b/spec/rubyspec/core/kernel/instance_variable_defined_spec.rb
@@ -0,0 +1,41 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes', __FILE__)
+
+describe "Kernel#instance_variable_defined?" do
+  before do
+    @instance = KernelSpecs::InstanceVariable.new
+  end
+
+  describe "when passed a String" do
+    it "returns false if the instance variable is not defined" do
+      @instance.instance_variable_defined?("@goodbye").should be_false
+    end
+
+    it "returns true if the instance variable is defined" do
+      @instance.instance_variable_defined?("@greeting").should be_true
+    end
+  end
+
+  describe "when passed a Symbol" do
+    it "returns false if the instance variable is not defined" do
+      @instance.instance_variable_defined?(:@goodbye).should be_false
+    end
+
+    it "returns true if the instance variable is defined" do
+      @instance.instance_variable_defined?(:@greeting).should be_true
+    end
+  end
+
+  it "raises a TypeError if passed an Object not defining #to_str" do
+    lambda do
+      obj = mock("kernel instance_variable_defined?")
+      @instance.instance_variable_defined? obj
+    end.should raise_error(TypeError)
+  end
+
+  it "returns false if the instance variable is not defined for different types" do
+    [nil, false, true, 1, 2.0, :test, "test"].each do |obj|
+      obj.instance_variable_defined?("@goodbye").should be_false
+    end
+  end
+end