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TDD - Scenario for Red, Green, Refactor

· One min read

Here's a really dumb scenario that will illustrate a point about the usefulness of the "red, green, refactor" approach to testing and coding. Here's the functionality - need to test whether or not a string has a value other than 1. Let's say I write a method before any tests:

public static bool MyMethod(string value)
{
    return value.Equals("1");
}

And let's say I write my test:

[Test]
public void t_MyMethod_NotOne()
{
    bool returnValue = false;
    MyMethod("2");
    Assert.IsFalse(returnValue);
}

The test will always pass! I wrote it incorrectly, I forgot to set returnValue = MyMethod("2"). If instead I had written this test with a "red, green, refactor" mindset, then I would have immediately seen that the test was green when it should be red — and then I would go back and realize that I had written the test incorrectly.

Good related links:

  1. Red-Green-Refactor (random blogger)
  2. Guidelines for Test-Driven Development (Microsoft)
  3. Unit Test Rulz (dead link removed; SF 2025) (random forum post)
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