1 files changed, 39 insertions, 0 deletions
diff --git a/spec/ruby/core/random/srand_spec.rb b/spec/ruby/core/random/srand_spec.rb
new file mode 100644
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+++ b/spec/ruby/core/random/srand_spec.rb
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+require File.expand_path('../../../spec_helper', __FILE__)
+
+describe "Random.srand" do
+  it "returns an arbitrary seed if .srand wasn't called previously with an argument and no argument is supplied this time" do
+    Random.srand # Reset to random seed in case .srand was called previously
+    Random.srand.should_not == Random.srand
+  end
+
+  it "returns the previous argument to .srand if one was given and no argument is supplied" do
+    Random.srand 34
+    Random.srand.should == 34
+  end
+
+  it "returns an arbitrary seed if .srand wasn't called previously with an argument and 0 is supplied this time" do
+    Random.srand # Reset to random seed in case .srand was called previously
+    Random.srand(0).should_not == Random.srand(0)
+  end
+
+  it "returns the previous argument to .srand if one was given and 0 is supplied" do
+    Random.srand 34
+    Random.srand(0).should == 34
+  end
+
+  it "seeds Random.rand such that its return value is deterministic" do
+    Random.srand 176542
+    a = 20.times.map { Random.rand }
+    Random.srand 176542
+    b = 20.times.map { Random.rand }
+    a.should == b
+  end
+
+  it "seeds Kernel.rand such that its return value is deterministic" do
+    Random.srand 176542
+    a = 20.times.map { Kernel.rand }
+    Random.srand 176542
+    b = 20.times.map { Kernel.rand }
+    a.should == b
+  end
+end