Test driven development
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Test-driven development (TDD) is a programming approach that integrates coding, testing, and design through a cycle of defining functionality, writing tests, and refactoring. An example is creating a string calculator with an 'add' function that processes multiple numbers and handles specific conditions like delimiters and negative numbers. The document emphasizes the importance of clean code and modularity in both tests and production code.
![Let’s try it
Create a simple String calculator with a method int Add(string numbers). The method can take 0, 1 or 2 numbers, and will
return their sum (for an empty string it will return 0) for example “” or “1” or “1,2”
Allow the Add method to handle an unknown amount of numbers
Allow the Add method to handle new lines between numbers (instead of commas).
The following input is ok: “1n2,3” (will equal 6)
Support different delimiters
To change a delimiter, the beginning of the string will contain a separate line that looks like this: “//[delimiter]n[numbers…]”
for example “//;n1;2” should return three where the default delimiter is ‘;’ .
The first line is optional. All existing scenarios should still be supported
Calling Add with a negative number will throw an exception “negatives not allowed” – and the negative that was passed. If
there are multiple negatives, show all of them in the exception message](https://image.slidesharecdn.com/testdrivendevelopment-170705065657/85/Test-driven-development-6-320.jpg)
Test driven development
- 2. Test Driven Development "Test-driven development" refers to a style of programming in which three activities are tightly interwoven: coding, testing (in the form of writing unit tests) and design (in the form of refactoring).
- 3. Unit Testing A software test is a piece of software, which executes another piece of software. Verify that your code is running correctly Provide documentation of code Catch future errors Long-term savings
- 4. Clean Unit Tests Test method name should be presented as a statement or fact of life that expresses workflows and outputs All test methods may be executed in an arbitrary order. Test cases should be fast Test code should be as clean and modular as regular code
- 5. The TDD Cycle Define what the code will do Write a test that will pass if the code does that thing Run the test, see it fail Write the code Run the test, see it pass Refactor
- 6. Let’s try it Create a simple String calculator with a method int Add(string numbers). The method can take 0, 1 or 2 numbers, and will return their sum (for an empty string it will return 0) for example “” or “1” or “1,2” Allow the Add method to handle an unknown amount of numbers Allow the Add method to handle new lines between numbers (instead of commas). The following input is ok: “1n2,3” (will equal 6) Support different delimiters To change a delimiter, the beginning of the string will contain a separate line that looks like this: “//[delimiter]n[numbers…]” for example “//;n1;2” should return three where the default delimiter is ‘;’ . The first line is optional. All existing scenarios should still be supported Calling Add with a negative number will throw an exception “negatives not allowed” – and the negative that was passed. If there are multiple negatives, show all of them in the exception message