🛤️ Path Coverage

📖 What Is Path Coverage?

Path coverage means choosing test data that ensures every possible path through the code is executed at least once. If your code has an if, elif, and else, you need test data that triggers EACH branch.

🐍 See It in Code

🐍 Path coverage for a Roblox rank system

# Roblox rank system with 3 paths
def get_rank(xp):
    if xp < 100:              # PATH A
        return "Noob"
    elif xp < 1000:           # PATH B
        return "Pro"
    else:                      # PATH C
        return "Legend"

# PATH COVERAGE: one test per path
tests = [
    (50,   "Noob",   "A"),   # triggers PATH A (xp < 100)
    (500,  "Pro",    "B"),   # triggers PATH B (100-999)
    (2000, "Legend", "C"),   # triggers PATH C (xp >= 1000)
]

print("=== PATH COVERAGE TESTS ===")
print(f"{'XP':<8} {'Expected':<10} {'Got':<10} {'Path':<6} {'Result'}")
print("-" * 50)
for xp, expected, path in tests:
    got = get_rank(xp)
    ok = "PASS" if got == expected else "FAIL"
    print(f"{xp:<8} {expected:<10} {got:<10} {path:<6} [{ok}]")

🎯 Path Coverage Rule

Count the number of branches in your code (each if, elif, else is a branch). You need at least one test case per branch. If you also have loops, test with: zero iterations, one iteration, and multiple iterations.