Debugging dengan pdb

Apa Itu pdb?

import pdb

def faulty(n):
    result = n * 2
    pdb.set_trace()   # execution pauses here
    return result + 1

faulty(5)

breakpoint() — Python 3.7+

def process(data):
    for item in data:
        if item < 0:
            breakpoint()   # drop into pdb here
        print(item)

process([1, -2, 3])

Perintah Inti pdb

# Inside pdb prompt:
# (Pdb) n          — execute next line
# (Pdb) s          — step into function
# (Pdb) c          — continue to next breakpoint
# (Pdb) p my_var   — print value
# (Pdb) l          — show source around current line
# (Pdb) q          — quit

Memeriksa Variabel

# (Pdb) p data
# [1, -2, 3]
# (Pdb) pp {"key": "value", "num": 42}
# {'key': 'value',
#  'num': 42}
# (Pdb) p locals()

Breakpoint Bersyarat

import pdb

def process(items):
    for i, item in enumerate(items):
        if item < 0:   # manual condition
            pdb.set_trace()
        result = item * 2

# Or inside pdb: b filename.py:12, x < 0

Debugging Pascakejadian

import pdb

try:
    1 / 0
except ZeroDivisionError:
    pdb.post_mortem()   # inspect at the crash point

# Or from CLI:
# python -m pdb my_script.py

Mengamati Variabel dengan w dan where

# (Pdb) w
# /app/main.py(10)main()
# -> process([1,-2,3])
# /app/main.py(5)process()
# -> breakpoint()

Berpindah Antar-Bingkai

# (Pdb) u   — move to calling frame
# (Pdb) d   — move back down
# (Pdb) p data   — inspect variable in that frame

ipdb — Alat Penelusuran Kesalahan yang Disempurnakan

# pip install ipdb
import ipdb

def calc(x):
    ipdb.set_trace()
    return x ** 2

calc(7)

pudb — Alat Penelusuran Kesalahan Terminal Visual

# pip install pudb
# python -m pudb my_script.py

import pudb

def run():
    pudb.set_trace()
    data = [1, 2, 3]
    return sum(data)

Menonaktifkan Titik Henti di CI

# In CI pipeline:
# export PYTHONBREAKPOINT=0
# python my_script.py
# breakpoint() is silently skipped

Pemeriksaan Cepat

Ringkasan