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

spec/rubyspec/library/complex/math/shared/sqrt.rb

@@ -0,0 +1,34 @@
+require File.expand_path('../../fixtures/classes', __FILE__)
+
+describe :complex_math_sqrt, shared: true do
+  it "returns the square root for positive numbers" do
+    @object.send(:sqrt, 4).should == 2
+    @object.send(:sqrt, 19.36).should == 4.4
+  end
+
+  it "returns the square root for negative numbers" do
+    @object.send(:sqrt, -4).should == Complex(0, 2.0)
+    @object.send(:sqrt, -19.36).should == Complex(0, 4.4)
+  end
+
+  it "returns the square root for Complex numbers" do
+    @object.send(:sqrt, Complex(4, 5)).should be_close(Complex(2.2806933416653, 1.09615788950152), TOLERANCE)
+    @object.send(:sqrt, Complex(4, -5)).should be_close(Complex(2.2806933416653, -1.09615788950152), TOLERANCE)
+  end
+end
+
+describe :complex_math_sqrt_bang, shared: true do
+  it "returns the square root for positive numbers" do
+    @object.send(:sqrt!, 4).should == 2
+    @object.send(:sqrt!, 19.36).should == 4.4
+  end
+
+  it "raises Errno::EDOM when the passed argument is negative" do
+    lambda { @object.send(:sqrt!, -4) }.should raise_error(Errno::EDOM)
+    lambda { @object.send(:sqrt!, -19.36) }.should raise_error(Errno::EDOM)
+  end
+
+  it "raises a TypeError when passed a Complex number" do
+    lambda { @object.send(:sqrt!, Complex(4, 5)) }.should raise_error(TypeError)
+  end
+end