Add in-tree mspec and ruby/spec

* For easier modifications of ruby/spec by MRI developers.
* .gitignore: track changes under spec.
* spec/mspec, spec/rubyspec: add in-tree mspec and ruby/spec.
  These files can therefore be updated like any other file in MRI.
  Instructions are provided in spec/README.
  [Feature #13156] [ruby-core:79246]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58595 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 56 insertions, 0 deletions

diff --git a/spec/rubyspec/core/math/lgamma_spec.rb b/spec/rubyspec/core/math/lgamma_spec.rb
new file mode 100644
index 0000000000..885a1b252c
--- /dev/null
+++ b/spec/rubyspec/core/math/lgamma_spec.rb
@@ -0,0 +1,56 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+describe "Math.lgamma" do
+  it "returns [Infinity, 1] when passed 0" do
+    Math.lgamma(0).should == [infinity_value, 1]
+  end
+
+  platform_is_not :windows do
+    it "returns [Infinity, 1] when passed -1" do
+      Math.lgamma(-1).should == [infinity_value, 1]
+    end
+  end
+
+  ruby_version_is "2.4" do
+    it "returns [Infinity, -1] when passed -0.0" do
+      Math.lgamma(-0.0).should == [infinity_value, -1]
+    end
+  end
+
+  it "returns [log(sqrt(PI)), 1] when passed 0.5" do
+    lg1 = Math.lgamma(0.5)
+    lg1[0].should be_close(Math.log(Math.sqrt(Math::PI)), TOLERANCE)
+    lg1[1].should == 1
+  end
+
+  it "returns [log(2/3*PI, 1] when passed 6.0" do
+    lg2 = Math.lgamma(6.0)
+    lg2[0].should be_close(Math.log(120.0), TOLERANCE)
+    lg2[1].should == 1
+  end
+
+  it "returns an approximate value when passed -0.5" do
+    lg1 = Math.lgamma(-0.5)
+    lg1[0].should be_close(1.2655121, TOLERANCE)
+    lg1[1].should == -1
+  end
+
+  it "returns an approximate value when passed -1.5" do
+    lg2 = Math.lgamma(-1.5)
+    lg2[0].should be_close(0.8600470, TOLERANCE)
+    lg2[1].should == 1
+  end
+
+  it "raises Math::DomainError when passed -Infinity" do
+    lambda { Math.lgamma(-infinity_value) }.should raise_error(Math::DomainError)
+  end
+
+  it "returns [Infinity, 1] when passed Infinity" do
+    Math.lgamma(infinity_value).should == [infinity_value, 1]
+  end
+
+  it "returns [NaN, 1] when passed NaN" do
+    Math.lgamma(nan_value)[0].nan?.should be_true
+    Math.lgamma(nan_value)[1].should == 1
+  end
+end