1 files changed, 41 insertions, 0 deletions
diff --git a/spec/ruby/core/math/log2_spec.rb b/spec/ruby/core/math/log2_spec.rb
new file mode 100644
index 0000000000..387f05ca9f
--- /dev/null
+++ b/spec/ruby/core/math/log2_spec.rb
@@ -0,0 +1,41 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes', __FILE__)
+
+describe "Math.log2" do
+  it "returns a float" do
+    Math.log2(5.79).should be_close(2.53356334821451, TOLERANCE)
+  end
+
+  it "returns the natural logarithm of the argument" do
+    Math.log2(1.1).should be_close(0.137503523749935, TOLERANCE)
+    Math.log2(3.14).should be_close(1.6507645591169, TOLERANCE)
+    Math.log2((2**101+45677544234809571)).should be_close(101.00000000000003, TOLERANCE)
+
+    Math.log2((2**10001+45677544234809571)).should == 10001.0
+    Math.log2((2**301+45677544234809571)).should == 301.0
+  end
+
+  it "raises an Errno::EDOM if the argument is less than 0" do
+    lambda { Math.log2(-1e-15) }.should raise_error( Math::DomainError)
+  end
+
+  it "raises a TypeError if the argument cannot be coerced with Float()" do
+    lambda { Math.log2("test") }.should raise_error(TypeError)
+  end
+
+  it "raises a TypeError if passed a numerical argument as a string" do
+    lambda { Math.log2("1.0") }.should raise_error(TypeError)
+  end
+
+  it "returns NaN given NaN" do
+    Math.log2(nan_value).nan?.should be_true
+  end
+
+  it "raises a TypeError if the argument is nil" do
+    lambda { Math.log2(nil) }.should raise_error(TypeError)
+  end
+
+  it "accepts any argument that can be coerced with Float()" do
+    Math.log2(MathSpecs::Float.new).should be_close(0.0, TOLERANCE)
+  end
+end