I am getting more comfortable with Clojure. For some reason I prefer functions, so writing in a functional language is nice.
I am learning new tricks that clojure can do which is quite impressive. Following the practices of TDD, it is necessary to test everything. Before in Python when I wanted to test an input from the user, or even what a printing would produce I would give up because I couldn’t find a nice and easy way to do this.
Now in Clojure you can test anything. Even inputs and printed information.
Here I have a test for the function update-board that takes the board initially with a boolean, and returns a new board with an X or O in its place. Now the point of update board is that you get a user input to replace a number and place your X or O into the board. How do you test user input?
In Clojure read-line is the built-in function that asks for the input. with-redefs is the function that can allow us to test whether the input works or not. with-redefs lets you temporarily change the definitions of functions within a specific block of code, then automatically switches them back to their original forms when you’re done.
(it "updates board for X"
(with-redefs [read-line (fn [] "1")]
(should= ["X" 2 3 4 5 6 7 8 9]
(sut/update-board [1 2 3 4 5 6 7 8 9] true))))
This allows us to test the code that uses an input successfully. That is pretty incredible.
Were also able to test the input twice using a new function with-in-str. In this test pressing 1 for player X then 2 for player O, allows us to test if the function would change the board in the correct manner. with-in-str is also nifty because it lets you temporarily redirect a function’s input to come from a specific string, instead of the usual keyboard input.
(it "updates board after two moves"
(with-in-str "1\n2\n"
(should= ["X" "O" 3 4 5 6 7 8 9]
(-> (sut/update-board [1 2 3 4 5 6 7 8 9] true)
(sut/update-board false)))))
Clojure is a pretty powerful language. I’m excited to continue to learn more and more.
Best,
Merl