ruby--ruby/spec/ruby/core/math/tanh_spec.rb

require File.expand_path('../../../spec_helper', __FILE__)
require File.expand_path('../fixtures/classes', __FILE__)

describe "Math.tanh" do
  it "returns a float" do
    Math.tanh(0.5).should be_kind_of(Float)
  end

  it "returns the hyperbolic tangent of the argument" do
    Math.tanh(0.0).should == 0.0
    Math.tanh(-0.0).should == -0.0
    Math.tanh(infinity_value).should == 1.0
    Math.tanh(-infinity_value).should == -1.0
    Math.tanh(2.5).should be_close(0.98661429815143, TOLERANCE)
    Math.tanh(-4.892).should be_close(-0.999887314427707, TOLERANCE)
  end

  it "raises a TypeError if the argument cannot be coerced with Float()" do
    lambda { Math.tanh("test") }.should raise_error(TypeError)
  end

  it "returns NaN given NaN" do
    Math.tanh(nan_value).nan?.should be_true
  end

  it "raises a TypeError if the argument is nil" do
    lambda { Math.tanh(nil) }.should raise_error(TypeError)
  end

  it "accepts any argument that can be coerced with Float()" do
    Math.tanh(MathSpecs::Float.new).should be_close(0.761594155955765, TOLERANCE)
  end
end

describe "Math#tanh" do
  it "is accessible as a private instance method" do
    IncludesMath.new.send(:tanh, 5.21).should be_close(0.99994034202065, TOLERANCE)
  end
end