Homework: Fix the Test Suite

作业: 修复测试套件

≈ 40 min · python-debugging · Open in WolfCode

Four broken functions. Each has exactly one bug — and each bug is a pattern you've seen before. The course capstone.

The four bugs

Function	Bug pattern	Where you've seen it
`letter_grade`	elif chain in wrong order	Ch.2 Letter Grade
`fizzbuzz`	append int instead of str	Ch.3 FizzBuzz
`word_starts_with`	`return` instead of `append`	Ch.6 search vs filter
`bisect_count`	off-by-one (missing `+ 1`)	Ch.3 Sum 1..n

The right fixes — for reference after submission

Python · runnable

# letter_grade — order tightest threshold first
if score >= 90:   return "A"
elif score >= 80: return "B"
elif score >= 70: return "C"
elif score >= 60: return "D"
else:             return "F"

# fizzbuzz — str(i), not i
else:
    result.append(str(i))

# word_starts_with — append, then return matches
for w in words:
    if w.startswith(prefix):
        matches.append(w)            # ← was: return w
return matches

# bisect_count — inclusive needs + 1
return hi - lo + 1

Loading Python runtime (~5 MB, one-time)…

Acceptance criteria

All 14 tests pass
Each fix is minimal — no rewriting from scratch
No new bugs introduced — run all tests after each fix

🎓 You've reached the end

This is the last graded homework in CSC 141. After this you can write, read, and debug any first-semester Python program. Welcome to programming.