1 files changed, 56 insertions, 0 deletions
diff --git a/spec/ruby/core/math/acos_spec.rb b/spec/ruby/core/math/acos_spec.rb
new file mode 100644
index 0000000000..4649dc527c
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+++ b/spec/ruby/core/math/acos_spec.rb
@@ -0,0 +1,56 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+# arccosine : (-1.0, 1.0) --> (0, PI)
+describe "Math.acos" do
+  before :each do
+    ScratchPad.clear
+  end
+
+  it "returns a float" do
+    Math.acos(1).should.is_a?(Float )
+  end
+
+  it "returns the arccosine of the argument" do
+    Math.acos(1).should be_close(0.0, TOLERANCE)
+    Math.acos(0).should be_close(1.5707963267949, TOLERANCE)
+    Math.acos(-1).should be_close(Math::PI,TOLERANCE)
+    Math.acos(0.25).should be_close(1.31811607165282, TOLERANCE)
+    Math.acos(0.50).should be_close(1.0471975511966 , TOLERANCE)
+    Math.acos(0.75).should be_close(0.722734247813416, TOLERANCE)
+  end
+
+  it "raises an Math::DomainError if the argument is greater than 1.0" do
+    -> { Math.acos(1.0001) }.should.raise(Math::DomainError)
+  end
+
+  it "raises an Math::DomainError if the argument is less than -1.0" do
+    -> { Math.acos(-1.0001) }.should.raise(Math::DomainError)
+  end
+
+  it "raises a TypeError if the string argument cannot be coerced with Float()" do
+    -> { Math.acos("test") }.should.raise(TypeError)
+  end
+
+  it "returns NaN given NaN" do
+    Math.acos(nan_value).nan?.should == true
+  end
+
+  it "raises a TypeError if the argument cannot be coerced with Float()" do
+    -> { Math.acos(MathSpecs::UserClass.new) }.should.raise(TypeError)
+  end
+
+  it "raises a TypeError if the argument is nil" do
+    -> { Math.acos(nil) }.should.raise(TypeError)
+  end
+
+  it "accepts any argument that can be coerced with Float()" do
+    Math.acos(MathSpecs::Float.new(0.5)).should be_close(Math.acos(0.5), TOLERANCE)
+  end
+end
+
+describe "Math#acos" do
+  it "is accessible as a private instance method" do
+    IncludesMath.new.send(:acos, 0).should be_close(1.5707963267949, TOLERANCE)
+  end
+end