World 10: Deep Git · Boss challenge

Detective: find the bug commit

You will learn: to track down the commit that broke a page, with bisect, a test and blame.

The problem

~/kedai $ git log --oneline0feda89 (HEAD -> main) Update footer year51b7e6e Add closing dayea24e01 Add a footer810fed2 Link the menu7108bd9 Add phone number7bb484d Clean up the form387e919 Fix button colour6187411 Add pickup timeaabe367 Add halal notef0d9953 Reword the title140a233 Add payment noteeca4c56 Add a note box9d62d7d Add a quantity boxcc77188 Add order page

Emergency at Kedai Kancil! The Buy button is greyed out. Nobody can order kuih. Fourteen suspects. Find the guilty commit, detective!

Try it

Your clue is test.sh. It runs ! grep -q "disabled" order.html. When does the test pass?

Try it

Round 1: question the suspects. Run the test, then mark each commit good or bad.

The oldest commit works. The newest one is broken. Find the first bad commit.

The test: the Buy button in order.html must not be disabled.

cc77188Add order pagegood
9d62d7dAdd a quantity boxmaybe
eca4c56Add a note boxmaybe
140a233Add payment notemaybe
f0d9953Reword the titlemaybe
aabe367Add halal notemaybe
6187411Add pickup timemaybe
387e919Fix button colourmaybe
7bb484dClean up the formmaybe
7108bd9Add phone numbermaybe
810fed2Link the menumaybe
ea24e01Add a footermaybe
51b7e6eAdd closing daymaybe
0feda89Update footer yearbad

Tests used: 0. For 13 commits, bisect needs at most 4.

Predict

“Fix button colour” sounds guilty. Was it?

Try it

Round 2: the real terminal. Start bisect, let test.sh judge every step, then go back to main.

Hint

git bisect start HEAD HEAD~13, then git bisect run sh test.sh, then git bisect reset.

Check

~/kedai $ git blame -L 6,6 order.html7bb484d (You 2026-10-30 09:09:00 +0800 6) <button disabled>Buy</button>

Double-check the evidence. git blame -L 6,6 names the last change to the button line. Same suspect!

Check

The culprit is already shared with the team. What is your next move?

You did it!

You can now find the commit that broke something, like a detective.