1 files changed, 41 insertions, 0 deletions
diff --git a/spec/ruby/core/math/acosh_spec.rb b/spec/ruby/core/math/acosh_spec.rb
new file mode 100644
index 0000000000..ccacda37e0
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+++ b/spec/ruby/core/math/acosh_spec.rb
@@ -0,0 +1,41 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Math.acosh" do
+  it "returns a float" do
+    Math.acosh(1.0).should.is_a?(Float)
+  end
+
+  it "returns the principle value of the inverse hyperbolic cosine of the argument" do
+    Math.acosh(14.2).should be_close(3.345146999647, TOLERANCE)
+    Math.acosh(1.0).should be_close(0.0, TOLERANCE)
+  end
+
+  it "raises Math::DomainError if the passed argument is less than -1.0 or greater than 1.0" do
+    -> { Math.acosh(1.0 - TOLERANCE) }.should.raise(Math::DomainError)
+    -> { Math.acosh(0) }.should.raise(Math::DomainError)
+    -> { Math.acosh(-1.0) }.should.raise(Math::DomainError)
+  end
+
+  it "raises a TypeError if the argument cannot be coerced with Float()" do
+    -> { Math.acosh("test") }.should.raise(TypeError)
+  end
+
+  it "returns NaN given NaN" do
+    Math.acosh(nan_value).nan?.should == true
+  end
+
+  it "raises a TypeError if the argument is nil" do
+    -> { Math.acosh(nil) }.should.raise(TypeError)
+  end
+
+  it "accepts any argument that can be coerced with Float()" do
+    Math.acosh(MathSpecs::Float.new).should == 0.0
+  end
+end
+
+describe "Math#acosh" do
+  it "is accessible as a private instance method" do
+    IncludesMath.new.send(:acosh, 1.0).should be_close(0.0, TOLERANCE)
+  end
+end