1 files changed, 76 insertions, 0 deletions
diff --git a/spec/ruby/core/fixnum/exponent_spec.rb b/spec/ruby/core/fixnum/exponent_spec.rb
new file mode 100644
index 0000000000..f3e7349ace
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+++ b/spec/ruby/core/fixnum/exponent_spec.rb
@@ -0,0 +1,76 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+describe "Fixnum#**" do
+  it "returns self raised to the given power" do
+    (2 ** 0).should eql 1
+    (2 ** 1).should eql 2
+    (2 ** 2).should eql 4
+
+    (9 ** 0.5).should eql 3.0
+    (5 ** -1).to_f.to_s.should == '0.2'
+
+    (2 ** 40).should eql 1099511627776
+  end
+
+  it "overflows the answer to a bignum transparantly" do
+    (2 ** 29).should eql 536870912
+    (2 ** 30).should eql 1073741824
+    (2 ** 31).should eql 2147483648
+    (2 ** 32).should eql 4294967296
+
+    (2 ** 61).should eql 2305843009213693952
+    (2 ** 62).should eql 4611686018427387904
+    (2 ** 63).should eql 9223372036854775808
+    (2 ** 64).should eql 18446744073709551616
+    (8 ** 23).should eql 590295810358705651712
+  end
+
+  it "raises negative numbers to the given power" do
+    ((-2) ** 29).should eql(-536870912)
+    ((-2) ** 30).should eql(1073741824)
+    ((-2) ** 31).should eql(-2147483648)
+    ((-2) ** 32).should eql(4294967296)
+
+    ((-2) ** 61).should eql(-2305843009213693952)
+    ((-2) ** 62).should eql(4611686018427387904)
+    ((-2) ** 63).should eql(-9223372036854775808)
+    ((-2) ** 64).should eql(18446744073709551616)
+  end
+
+  it "can raise 1 to a Bignum safely" do
+    big = bignum_value(4611686018427387904)
+    (1 ** big).should eql 1
+  end
+
+  it "can raise -1 to a Bignum safely" do
+    ((-1) ** bignum_value(0)).should eql(1)
+    ((-1) ** bignum_value(1)).should eql(-1)
+  end
+
+  it "switches to a Float when the number is too big" do
+    big = bignum_value(4611686018427387904)
+    flt = (2 ** big)
+    flt.should be_kind_of(Float)
+    flt.infinite?.should == 1
+  end
+
+  conflicts_with :Rational do
+    it "raises a ZeroDivisionError for 0**-1" do
+      lambda { (0**-1) }.should raise_error(ZeroDivisionError)
+    end
+
+    it "raises a TypeError when given a non-Integer" do
+      lambda {
+        (obj = mock('10')).should_receive(:to_int).any_number_of_times.and_return(10)
+        13 ** obj
+      }.should raise_error(TypeError)
+      lambda { 13 ** "10"    }.should raise_error(TypeError)
+      lambda { 13 ** :symbol }.should raise_error(TypeError)
+    end
+  end
+
+  it "returns a complex number when negative and raised to a fractional power" do
+    ((-8) ** (1.0/3))      .should be_close(Complex(1, 1.73205), TOLERANCE)
+    ((-8) ** Rational(1,3)).should be_close(Complex(1, 1.73205), TOLERANCE)
+  end
+end