1 files changed, 51 insertions, 0 deletions
diff --git a/spec/ruby/core/rational/minus_spec.rb b/spec/ruby/core/rational/minus_spec.rb
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+++ b/spec/ruby/core/rational/minus_spec.rb
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+require_relative '../../spec_helper'
+require_relative 'shared/arithmetic_exception_in_coerce'
+
+describe "Rational#-" do
+  it_behaves_like :rational_arithmetic_exception_in_coerce, :-
+
+  it "calls #coerce on the passed argument with self" do
+    rational = Rational(3, 4)
+    obj = mock("Object")
+    obj.should_receive(:coerce).with(rational).and_return([1, 2])
+
+    rational - obj
+  end
+
+  it "calls #- on the coerced Rational with the coerced Object" do
+    rational = Rational(3, 4)
+
+    coerced_rational = mock("Coerced Rational")
+    coerced_rational.should_receive(:-).and_return(:result)
+
+    coerced_obj = mock("Coerced Object")
+
+    obj = mock("Object")
+    obj.should_receive(:coerce).and_return([coerced_rational, coerced_obj])
+
+    (rational - obj).should == :result
+  end
+end
+
+describe "Rational#- passed a Rational" do
+  it "returns the result of subtracting other from self as a Rational" do
+    (Rational(3, 4) - Rational(0, 1)).should.eql?(Rational(3, 4))
+    (Rational(3, 4) - Rational(1, 4)).should.eql?(Rational(1, 2))
+
+    (Rational(3, 4) - Rational(2, 1)).should.eql?(Rational(-5, 4))
+  end
+end
+
+describe "Rational#- passed a Float" do
+  it "returns the result of subtracting other from self as a Float" do
+    (Rational(3, 4) - 0.2).should.eql?(0.55)
+    (Rational(3, 4) - 2.5).should.eql?(-1.75)
+  end
+end
+
+describe "Rational#- passed an Integer" do
+  it "returns the result of subtracting other from self as a Rational" do
+    (Rational(3, 4) - 1).should.eql?(Rational(-1, 4))
+    (Rational(3, 4) - 2).should.eql?(Rational(-5, 4))
+  end
+end