rails float type number does not work right

  describe "common methods" do

    it "should get right settlement percent" do
      contract = Contract.new
      contract.settlement_percent = 1.1 / 100.0
      contrac开发者_运维百科t.settlement_percent.to_f.should == 0.011 
      contract.settlement_percent.to_s.should == "0.011"
    end

  end

1) Contract common methods should 
 Failure/Error: contract.settlement_percent.to_f.should == 0.011
 expected: 0.011,
      got: 0.011000000000000001 (using ==)

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You can use the be_close method to account for this approximation issue. Just pass it the value and how close you want the comparison to be.

Something like this should work for you:

contract.settlement_percent.to_f.should be_close(0.011, 0.0001)

A little more on be_close here...

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Base-10 floating point values are always approximated since they're encoded in binary. You shouldn't expect values to be that precise.

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Take a look at this post: What is the most effective way for float and double comparison?