1 files changed, 197 insertions, 0 deletions
diff --git a/spec/ruby/core/kernel/rand_spec.rb b/spec/ruby/core/kernel/rand_spec.rb
new file mode 100644
index 0000000000..355e425792
--- /dev/null
+++ b/spec/ruby/core/kernel/rand_spec.rb
@@ -0,0 +1,197 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Kernel#rand" do
+  it "is a private method" do
+    Kernel.should have_private_instance_method(:rand)
+  end
+
+  it "returns a float if no argument is passed" do
+    rand.should be_kind_of(Float)
+  end
+
+  it "returns an integer for an integer argument" do
+    rand(77).should be_kind_of(Integer)
+  end
+
+  it "returns an integer for a float argument greater than 1" do
+    rand(1.3).should be_kind_of(Integer)
+  end
+
+  it "returns a float for an argument between -1 and 1" do
+    rand(-0.999).should be_kind_of(Float)
+    rand(-0.01).should be_kind_of(Float)
+    rand(0).should be_kind_of(Float)
+    rand(0.01).should be_kind_of(Float)
+    rand(0.999).should be_kind_of(Float)
+  end
+
+  it "ignores the sign of the argument" do
+    [0, 1, 2, 3].should include(rand(-4))
+  end
+
+  it "never returns a value greater or equal to 1.0 with no arguments" do
+    1000.times do
+      (0...1.0).should include(rand)
+    end
+  end
+
+  it "never returns a value greater or equal to any passed in max argument" do
+    1000.times do
+      (0...100).to_a.should include(rand(100))
+    end
+  end
+
+  it "calls to_int on its argument" do
+    l = mock('limit')
+    l.should_receive(:to_int).and_return 7
+
+    rand l
+  end
+
+  context "given an exclusive range" do
+    it "returns an Integer between the two Integers" do
+      1000.times do
+        x = rand(4...6)
+        x.should be_kind_of(Integer)
+        (4...6).should include(x)
+      end
+    end
+
+    it "returns a Float between the given Integer and Float" do
+      1000.times do
+        x = rand(4...6.5)
+        x.should be_kind_of(Float)
+        (4...6.5).should include(x)
+      end
+    end
+
+    it "returns a Float between the given Float and Integer" do
+      1000.times do
+        x = rand(3.5...6)
+        x.should be_kind_of(Float)
+        (3.5...6).should include(x)
+      end
+    end
+
+    it "returns a Float between the two given Floats" do
+      1000.times do
+        x = rand(3.5...6.5)
+        x.should be_kind_of(Float)
+        (3.5...6.5).should include(x)
+      end
+    end
+  end
+
+  context "given an inclusive range" do
+    it "returns an Integer between the two Integers" do
+      1000.times do
+        x = rand(4..6)
+        x.should be_kind_of(Integer)
+        (4..6).should include(x)
+      end
+    end
+
+    it "returns a Float between the given Integer and Float" do
+      1000.times do
+        x = rand(4..6.5)
+        x.should be_kind_of(Float)
+        (4..6.5).should include(x)
+      end
+    end
+
+    it "returns a Float between the given Float and Integer" do
+      1000.times do
+        x = rand(3.5..6)
+        x.should be_kind_of(Float)
+        (3.5..6).should include(x)
+      end
+    end
+
+    it "returns a Float between the two given Floats" do
+      1000.times do
+        x = rand(3.5..6.5)
+        x.should be_kind_of(Float)
+        (3.5..6.5).should include(x)
+      end
+    end
+  end
+
+  context "given an inclusive range between 0 and 1" do
+    it "returns an Integer between the two Integers" do
+      x = rand(0..1)
+      x.should be_kind_of(Integer)
+      (0..1).should include(x)
+    end
+
+    it "returns a Float if at least one side is Float" do
+      seed = 42
+      x1 = Random.new(seed).rand(0..1.0)
+      x2 = Random.new(seed).rand(0.0..1.0)
+      x3 = Random.new(seed).rand(0.0..1)
+
+      x3.should be_kind_of(Float)
+      x1.should eql(x3)
+      x2.should eql(x3)
+
+      (0.0..1.0).should include(x3)
+    end
+  end
+
+  context "given an exclusive range between 0 and 1" do
+    it "returns zero as an Integer" do
+      x = rand(0...1)
+      x.should be_kind_of(Integer)
+      x.should eql(0)
+    end
+
+    it "returns a Float if at least one side is Float" do
+      seed = 42
+      x1 = Random.new(seed).rand(0...1.0)
+      x2 = Random.new(seed).rand(0.0...1.0)
+      x3 = Random.new(seed).rand(0.0...1)
+
+      x3.should be_kind_of(Float)
+      x1.should eql(x3)
+      x2.should eql(x3)
+
+      (0.0...1.0).should include(x3)
+    end
+  end
+
+  it "returns a numeric for an range argument where max is < 1" do
+    rand(0.25..0.75).should be_kind_of(Numeric)
+  end
+
+  it "returns nil when range is backwards" do
+    rand(1..0).should be_nil
+  end
+
+  it "returns the range start/end when Float range is 0" do
+    rand(1.0..1.0).should eql(1.0)
+  end
+
+  it "returns the range start/end when Integer range is 0" do
+    rand(42..42).should eql(42)
+  end
+
+  it "supports custom object types" do
+    rand(KernelSpecs::CustomRangeInteger.new(1)..KernelSpecs::CustomRangeInteger.new(42)).should be_an_instance_of(KernelSpecs::CustomRangeInteger)
+    rand(KernelSpecs::CustomRangeFloat.new(1.0)..KernelSpecs::CustomRangeFloat.new(42.0)).should be_an_instance_of(KernelSpecs::CustomRangeFloat)
+    rand(Time.now..Time.now).should be_an_instance_of(Time)
+  end
+
+  it "is random on boot" do
+    results = 2.times.map {
+      out = ruby_exe('p rand', options: '--disable-gems')
+      Float(out)
+    }
+    results.size.should == 2
+    # this is technically flaky, but very unlikely in a good distribution
+    results[0].should_not == results[1]
+  end
+end
+
+describe "Kernel.rand" do
+  it "needs to be reviewed for spec completeness"
+end