1 files changed, 40 insertions, 0 deletions
diff --git a/spec/ruby/core/math/atan_spec.rb b/spec/ruby/core/math/atan_spec.rb
new file mode 100644
index 0000000000..6787479cd9
--- /dev/null
+++ b/spec/ruby/core/math/atan_spec.rb
@@ -0,0 +1,40 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes', __FILE__)
+
+# arctangent : (-Inf, Inf) --> (-PI/2, PI/2)
+describe "Math.atan" do
+  it "returns a float" do
+    Math.atan(1).should be_kind_of(Float)
+  end
+
+  it "returns the arctangent of the argument" do
+    Math.atan(1).should be_close(Math::PI/4, TOLERANCE)
+    Math.atan(0).should be_close(0.0, TOLERANCE)
+    Math.atan(-1).should be_close(-Math::PI/4, TOLERANCE)
+    Math.atan(0.25).should be_close(0.244978663126864, TOLERANCE)
+    Math.atan(0.50).should be_close(0.463647609000806, TOLERANCE)
+    Math.atan(0.75).should be_close(0.643501108793284, TOLERANCE)
+  end
+
+  it "raises a TypeError if the argument cannot be coerced with Float()" do
+    lambda { Math.atan("test") }.should raise_error(TypeError)
+  end
+
+  it "returns NaN given NaN" do
+    Math.atan(nan_value).nan?.should be_true
+  end
+
+  it "raises a TypeError if the argument is nil" do
+    lambda { Math.atan(nil) }.should raise_error(TypeError)
+  end
+
+  it "accepts any argument that can be coerced with Float()" do
+    Math.atan(MathSpecs::Float.new).should be_close(0.785398163397448, TOLERANCE)
+  end
+end
+
+describe "Math#atan" do
+  it "is accessible as a private instance method" do
+    IncludesMath.new.send(:atan, 3.1415).should be_close(1.2626187313511, TOLERANCE)
+  end
+end