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require_relative '../../spec_helper'
describe "Float#next_float" do
it "returns a float the smallest possible step greater than the receiver" do
barely_positive = 0.0.next_float
barely_positive.should == 0.0.next_float
barely_positive.should > 0.0
barely_positive.should < barely_positive.next_float
midpoint = barely_positive / 2
[0.0, barely_positive].should include midpoint
end
it "returns Float::INFINITY for Float::INFINITY" do
Float::INFINITY.next_float.should == Float::INFINITY
end
it "steps directly between MAX and INFINITY" do
(-Float::INFINITY).next_float.should == -Float::MAX
Float::MAX.next_float.should == Float::INFINITY
end
it "steps directly between 1.0 and 1.0 + EPSILON" do
1.0.next_float.should == 1.0 + Float::EPSILON
end
it "steps directly between -1.0 and -1.0 + EPSILON/2" do
(-1.0).next_float.should == -1.0 + Float::EPSILON/2
end
it "reverses the effect of prev_float for all Floats except INFINITY and +0.0" do
num = -rand
num.prev_float.next_float.should == num
end
it "returns negative zero when stepping upward from just below zero" do
x = (-0.0).prev_float.next_float
(1/x).should == -Float::INFINITY
end
it "gives the same result for -0.0 as for +0.0" do
(-0.0).next_float.should == (0.0).next_float
end
it "returns NAN if NAN was the receiver" do
Float::NAN.next_float.should.nan?
end
end
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