1 files changed, 42 insertions, 0 deletions
diff --git a/spec/ruby/core/math/cos_spec.rb b/spec/ruby/core/math/cos_spec.rb
new file mode 100644
index 0000000000..59b23b198b
--- /dev/null
+++ b/spec/ruby/core/math/cos_spec.rb
@@ -0,0 +1,42 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes', __FILE__)
+
+# cosine : (-Inf, Inf) --> (-1.0, 1.0)
+describe "Math.cos" do
+  it "returns a float" do
+    Math.cos(Math::PI).should be_kind_of(Float)
+  end
+
+  it "returns the cosine of the argument expressed in radians" do
+    Math.cos(Math::PI).should be_close(-1.0, TOLERANCE)
+    Math.cos(0).should be_close(1.0, TOLERANCE)
+    Math.cos(Math::PI/2).should be_close(0.0, TOLERANCE)
+    Math.cos(3*Math::PI/2).should be_close(0.0, TOLERANCE)
+    Math.cos(2*Math::PI).should be_close(1.0, TOLERANCE)
+  end
+
+
+  it "raises a TypeError unless the argument is Numeric and has #to_f" do
+    lambda { Math.cos("test") }.should raise_error(TypeError)
+  end
+
+  it "returns NaN given NaN" do
+    Math.cos(nan_value).nan?.should be_true
+  end
+
+  it "raises a TypeError if the argument is nil" do
+    lambda { Math.cos(nil) }.should raise_error(TypeError)
+  end
+
+  it "coerces its argument with #to_f" do
+    f = mock_numeric('8.2')
+    f.should_receive(:to_f).and_return(8.2)
+    Math.cos(f).should == Math.cos(8.2)
+  end
+end
+
+describe "Math#cos" do
+  it "is accessible as a private instance method" do
+    IncludesMath.new.send(:cos, 3.1415).should be_close(-0.999999995707656, TOLERANCE)
+  end
+end