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Diffstat (limited to 'spec/ruby/core/random/rand_spec.rb')
-rw-r--r-- | spec/ruby/core/random/rand_spec.rb | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/spec/ruby/core/random/rand_spec.rb b/spec/ruby/core/random/rand_spec.rb new file mode 100644 index 0000000000..e0cb133abd --- /dev/null +++ b/spec/ruby/core/random/rand_spec.rb @@ -0,0 +1,216 @@ +require File.expand_path('../../../spec_helper', __FILE__) + +describe "Random.rand" do + it "returns a Float if no max argument is passed" do + Random.rand.should be_kind_of(Float) + end + + it "returns a Float >= 0 if no max argument is passed" do + floats = 200.times.map { Random.rand } + floats.min.should >= 0 + end + + it "returns a Float < 1 if no max argument is passed" do + floats = 200.times.map { Random.rand } + floats.max.should < 1 + end + + it "returns the same sequence for a given seed if no max argument is passed" do + Random.srand 33 + floats_a = 20.times.map { Random.rand } + Random.srand 33 + floats_b = 20.times.map { Random.rand } + floats_a.should == floats_b + end + + it "returns an Integer if an Integer argument is passed" do + Random.rand(20).should be_kind_of(Integer) + end + + it "returns an Integer >= 0 if an Integer argument is passed" do + ints = 200.times.map { Random.rand(34) } + ints.min.should >= 0 + end + + it "returns an Integer < the max argument if an Integer argument is passed" do + ints = 200.times.map { Random.rand(55) } + ints.max.should < 55 + end + + it "returns the same sequence for a given seed if an Integer argument is passed" do + Random.srand 33 + floats_a = 20.times.map { Random.rand(90) } + Random.srand 33 + floats_b = 20.times.map { Random.rand(90) } + floats_a.should == floats_b + end + + it "coerces arguments to Integers with #to_int" do + obj = mock_numeric('int') + obj.should_receive(:to_int).and_return(99) + Random.rand(obj).should be_kind_of(Integer) + end +end + +describe "Random#rand with Fixnum" do + it "returns an Integer" do + Random.new.rand(20).should be_an_instance_of(Fixnum) + end + + it "returns a Fixnum greater than or equal to 0" do + prng = Random.new + ints = 20.times.map { prng.rand(5) } + ints.min.should >= 0 + end + + it "returns a Fixnum less than the argument" do + prng = Random.new + ints = 20.times.map { prng.rand(5) } + ints.max.should <= 4 + end + + it "returns the same sequence for a given seed" do + prng = Random.new 33 + a = 20.times.map { prng.rand(90) } + prng = Random.new 33 + b = 20.times.map { prng.rand(90) } + a.should == b + end + + it "eventually returns all possible values" do + prng = Random.new 33 + 100.times.map{ prng.rand(10) }.uniq.sort.should == (0...10).to_a + end + + it "raises an ArgumentError when the argument is 0" do + lambda do + Random.new.rand(0) + end.should raise_error(ArgumentError) + end + + it "raises an ArgumentError when the argument is negative" do + lambda do + Random.new.rand(-12) + end.should raise_error(ArgumentError) + end +end + +describe "Random#rand with Bignum" do + it "typically returns a Bignum" do + rnd = Random.new(1) + 10.times.map{ rnd.rand(bignum_value*2) }.max.should be_an_instance_of(Bignum) + end + + it "returns a Bignum greater than or equal to 0" do + prng = Random.new + bigs = 20.times.map { prng.rand(bignum_value) } + bigs.min.should >= 0 + end + + it "returns a Bignum less than the argument" do + prng = Random.new + bigs = 20.times.map { prng.rand(bignum_value) } + bigs.max.should < bignum_value + end + + it "returns the same sequence for a given seed" do + prng = Random.new 33 + a = 20.times.map { prng.rand(bignum_value) } + prng = Random.new 33 + b = 20.times.map { prng.rand(bignum_value) } + a.should == b + end + + it "raises an ArgumentError when the argument is negative" do + lambda do + Random.new.rand(-bignum_value) + end.should raise_error(ArgumentError) + end +end + +describe "Random#rand with Float" do + it "returns a Float" do + Random.new.rand(20.43).should be_an_instance_of(Float) + end + + it "returns a Float greater than or equal to 0.0" do + prng = Random.new + floats = 20.times.map { prng.rand(5.2) } + floats.min.should >= 0.0 + end + + it "returns a Float less than the argument" do + prng = Random.new + floats = 20.times.map { prng.rand(4.30) } + floats.max.should < 4.30 + end + + it "returns the same sequence for a given seed" do + prng = Random.new 33 + a = 20.times.map { prng.rand(89.2928) } + prng = Random.new 33 + b = 20.times.map { prng.rand(89.2928) } + a.should == b + end + + it "raises an ArgumentError when the argument is negative" do + lambda do + Random.new.rand(-1.234567) + end.should raise_error(ArgumentError) + end +end + +describe "Random#rand with Range" do + it "returns an element from the Range" do + Random.new.rand(20..43).should be_an_instance_of(Fixnum) + end + + it "returns an object that is a member of the Range" do + prng = Random.new + r = 20..30 + 20.times { r.member?(prng.rand(r)).should be_true } + end + + it "works with inclusive ranges" do + prng = Random.new 33 + r = 3..5 + 40.times.map { prng.rand(r) }.uniq.sort.should == [3,4,5] + end + + it "works with exclusive ranges" do + prng = Random.new 33 + r = 3...5 + 20.times.map { prng.rand(r) }.uniq.sort.should == [3,4] + end + + it "returns the same sequence for a given seed" do + prng = Random.new 33 + a = 20.times.map { prng.rand(76890.028..800000.00) } + prng = Random.new 33 + b = 20.times.map { prng.rand(76890.028..800000.00) } + a.should == b + end + + it "eventually returns all possible values" do + prng = Random.new 33 + 100.times.map{ prng.rand(10..20) }.uniq.sort.should == (10..20).to_a + 100.times.map{ prng.rand(10...20) }.uniq.sort.should == (10...20).to_a + end + + it "considers Integers as Floats if one end point is a float" do + Random.new(42).rand(0.0..1).should be_kind_of(Float) + Random.new(42).rand(0..1.0).should be_kind_of(Float) + end + + it "raises an ArgumentError when the startpoint lacks #+ and #- methods" do + lambda do + Random.new.rand(Object.new..67) + end.should raise_error(ArgumentError) + end + + it "raises an ArgumentError when the endpoint lacks #+ and #- methods" do + lambda do + Random.new.rand(68..Object.new) + end.should raise_error(ArgumentError) + end +end |