1 files changed, 50 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..e8602cde3c
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+++ b/spec/ruby/core/math/cos_spec.rb
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+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+# cosine : (-Inf, Inf) --> (-1.0, 1.0)
+describe "Math.cos" do
+  it "returns a float" do
+    Math.cos(Math::PI).should.is_a?(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
+    -> { Math.cos("test") }.should.raise(TypeError)
+  end
+
+  it "returns NaN given NaN" do
+    Math.cos(nan_value).nan?.should == true
+  end
+
+  describe "coerces its argument with #to_f" do
+    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
+
+    it "raises a TypeError if the given argument can't be converted to a Float" do
+      -> { Math.cos(nil) }.should.raise(TypeError)
+      -> { Math.cos(:abc) }.should.raise(TypeError)
+    end
+
+    it "raises a NoMethodError if the given argument raises a NoMethodError during type coercion to a Float" do
+      object = mock_numeric('mock-float')
+      object.should_receive(:to_f).and_raise(NoMethodError)
+      -> { Math.cos(object) }.should.raise(NoMethodError)
+    end
+  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