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/core/numeric/coerce_spec.rb

@@ -0,0 +1,76 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes', __FILE__)
+
+describe "Numeric#coerce" do
+  before :each do
+    @obj = NumericSpecs::Subclass.new
+    @obj.should_receive(:to_f).any_number_of_times.and_return(10.5)
+  end
+
+  it "returns [other, self] if self and other are instances of the same class" do
+    a = NumericSpecs::Subclass.new
+    b = NumericSpecs::Subclass.new
+
+    a.coerce(b).should == [b, a]
+  end
+
+  # I (emp) think that this behavior is actually a bug in MRI. It's here as documentation
+  # of the behavior until we find out if it's a bug.
+  quarantine! do
+    it "considers the presense of a metaclass when checking the class of the objects" do
+      a = NumericSpecs::Subclass.new
+      b = NumericSpecs::Subclass.new
+
+      # inject a metaclass on a
+      class << a; true; end
+
+      # watch it explode
+      lambda { a.coerce(b) }.should raise_error(TypeError)
+    end
+  end
+
+  it "calls #to_f to convert other if self responds to #to_f" do
+    # Do not use NumericSpecs::Subclass here, because coerce checks the classes of the receiver
+    # and arguments before calling #to_f.
+    other = mock("numeric")
+    lambda { @obj.coerce(other) }.should raise_error(TypeError)
+  end
+
+  it "returns [other.to_f, self.to_f] if self and other are instances of different classes" do
+    result = @obj.coerce(2.5)
+    result.should == [2.5, 10.5]
+    result.first.should be_kind_of(Float)
+    result.last.should be_kind_of(Float)
+
+    result = @obj.coerce(3)
+    result.should == [3.0, 10.5]
+    result.first.should be_kind_of(Float)
+    result.last.should be_kind_of(Float)
+
+    result = @obj.coerce("4.4")
+    result.should == [4.4, 10.5]
+    result.first.should be_kind_of(Float)
+    result.last.should be_kind_of(Float)
+
+    result = @obj.coerce(bignum_value)
+    result.should == [bignum_value.to_f, 10.5]
+    result.first.should be_kind_of(Float)
+    result.last.should be_kind_of(Float)
+  end
+
+  it "raises a TypeError when passed nil" do
+    lambda { @obj.coerce(nil)     }.should raise_error(TypeError)
+  end
+
+  it "raises a TypeError when passed a boolean" do
+    lambda { @obj.coerce(false)   }.should raise_error(TypeError)
+  end
+
+  it "raises a TypeError when passed a Symbol" do
+    lambda { @obj.coerce(:symbol) }.should raise_error(TypeError)
+  end
+
+  it "raises an ArgumentError when passed a String" do
+    lambda { @obj.coerce("test")  }.should raise_error(ArgumentError)
+  end
+end