Powershell TDDMichael Willis

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Following concept from https://laracasts.com/series/code-katas-in-php/episodes/2

This following is an except from a class presentation.

Test-Driven Development

1. Write a test case for some code that has yet to be implemented

2. Run the test case to verify it, which fails

3. Write only as much code as necessary to make the test pass

4. Run the test case

Roman Numeral Calculator

1 => I; Write the test; Watch it fail.

Simplest implementation to make it pass

Returning “I” brings us to “Green”

2 => II; Write Test; Watch it Fail

Strategies

Two simple ways to make this pass. We chose to use the second method.

5 => V; Write Test; Watch it Fail.

Make V=>5 Pass.

Add VI => 6 to Tests; Watch it fail

Refactoring to use a $solution variable.

Testing after Refactor; 6 still fails.

Remove the Else statement. Still Failing tests for 5 & 6.

Add minimal code to make test pass.

X => 10; Write Test; Watch it Fail.

Code duplication pattern becoming apparent

Write Test for 11=>XI

Test is already passing; Move on to next edge case.

20 => XX; Write Test; Watch it Fail.

Changing “if” to “while” lets this logic run twice for 20 making the test pass.

50 => L; Write Test; Watch it Fail.

Duplicate code shows us that we may have room for refactoring.

4 => IV; Write Test; Watch it Fail.

Make 4 Pass

Test for 9 is added.After 9 Fails we duplicate the code from 10 and change it to make 9 pass.

Refactor to pattern

Other if statements will also pass using a while statement.

Refactor (cont.)

The Statement

can be refactored to use a while loop as well.

Refactor

Duplicate code removed by using a lookup hashtable. Test by removing the: while “$Number -ge 50 loop.”

Tests still Green!

Remove >= 10 Loop; Fail since Lookup missing X.

Add 10 = “X” to lookup; Back to Green.

Remove all other while loops; Add Values to lookup.

Why is L Failing?

Hashtables are not sorted.

Missing Edge Cases

Back to Green!

Community Help

Team integration apps can help with on the fly code review / testing.

Almost forgot the sunflower