test-doubles.md
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@@ -72,12 +72,18 @@ class ConverterTest < MiniTest::Test
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@c = Converter.new(FToCConverter)
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end
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- def test_f_to_c
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+ def test_convert
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assert_in_delta 500, @c.convert(32), 0.01
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end
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end
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```
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+**NOTE:** In the real world, this is not how it's done. Why? Because in this test, _we don't care about
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+FToCConverter_. All we care about is making available to the test an object that exposes a `convert`
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+method that returns a specific value, so that we van validate that the main `convert` method on
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+`Converter` leverages it. In short, we want to write the least amount of code to see that the plumbing
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+is working.
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+
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### Testing messages sent to others
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When we send a message to another object that results in a side effect, we want to verify the side effect.