paulroub/tcr-kata

TCR kata

Skeleton of a very simple TCR (test && commit || revert) setup.

Each time the script is run, if all tests succeed we commit all changes.

If tests fail, we revert any production code changes (but not tests) since the last commit.

The process

1. Write a test
2. ./tcr to confirm the test fails
3. Write enough just enough code to pass the test
4. ./tcr to get to green and commit (or revert, and go back to step 1, if we fail)
5. Write "real" code if needed to pass the tests honestly
6. ./tcr to get to green and commit (or revert, and go back to step 1, if we fail)
7. Repeat

Advanced version

Run ./tcrloop while coding. This will run the test/commit/revert script every time a file is edited and the files are in a compilable state.

After a successful (or reversion) the script will attempt to git pull and git push.

The exercise - Magic Square

Write a function to validate 3x3 magic squares. A magic square is one where all rows, all columns, and both diagonals sum to the same total. For 3x3 magic squares containing the digits 1-9, that total will be 15 in all directions.

Input

A 3x3 array of integers:

[
    [1,2,3],
    [4,5,6],
    [7,8,9]
]

(the above is not a valid matching square; for example, the first row sums to 6 while the last sums to 24)

Output

true if the magic square is valid, false otherwise.

Tests

1. Size must be 3x3
2. All digits 1-9 must be present
3. Each row sums to 15
4. Each column sums to 15
5. Each diagonal (top left + center + bottom right, top right + center + bottom left) sums to 15

Sample valid magic squares:

[
    [2, 7, 6],
    [9, 5, 1],
    [4, 3, 8]
]

[
    [4, 9, 2],
    [3, 5, 7],
    [8, 1, 6]
]

Preliminaries

Install the entr utility from Homebrew, by running brew install entr.

Run npm install in this folder to install needed node dependencies.