Fixing Unclear Pre-Push Error For Large PRs

Hey guys! Ever run into a cryptic error message when trying to push your code? It's super frustrating, especially when you're not sure what went wrong. This article dives into a specific issue we encountered with our pre-push hook and how we made the error messages way more helpful. Let's get started!

The Problem: A Vague Error Message

So, the situation was this: we have a pre-push hook set up to prevent pull requests (PRs) from getting too massive. Specifically, we have a limit of 600 lines of code changed per PR. This is a good practice because smaller PRs are easier to review, understand, and merge. However, when someone tried to push changes that exceeded this limit, they got hit with this incredibly unhelpful error message:

error: failed to push some refs to 'github.com:SecPal/api.git'

Yeah, that's it. No explanation, no hints, just a generic "failed to push" message. Imagine the confusion! You'd be scratching your head, wondering what went wrong. Was it a network issue? Did I mess up my Git config? Did the build break? It's like getting a cryptic error in a video game with no walkthrough in sight! This lack of clarity is a real productivity killer because it forces developers to spend time digging around to figure out the root cause instead of focusing on coding. A clear error message, on the other hand, acts like a helpful guide, pointing you directly to the problem and saving you precious time.

Why This Matters: The Importance of Clear Error Messages

Think of error messages as the user interface of your development workflow. They're how the system communicates problems to you. A good error message is like a friendly neighbor, offering clear and concise help. A bad error message is like a grumpy troll, leaving you to fend for yourself in the dark forest of debugging. Clear error messages are incredibly important for a few key reasons:

• They save time: A descriptive error message lets you quickly identify the problem and start working on a solution. No more digging through logs or guessing games!
• They reduce frustration: Let's be honest, debugging can be stressful enough. A helpful error message can ease the pain and prevent you from throwing your keyboard across the room. We've all been there, right?
• They improve code quality: When errors are easy to understand, developers are more likely to fix them correctly and learn from their mistakes. It's like having a helpful teacher guiding you through the process.
• They make onboarding easier: Clear error messages help new team members get up to speed quickly. They can understand the project's rules and constraints without having to ask for help constantly. This is huge for team efficiency and morale.

In our case, the vague error message was a major pain point. It violated the fundamental principle of good error messaging: tell the user what went wrong and what they can do about it. We needed to fix this, stat!

The Expected Behavior: A Helpful Error Message

So, what should the error message have said? We envisioned something much more informative, like this:

❌ Pre-push check failed: PR too large

Your changes contain 644 lines (636 insertions, 8 deletions).
Maximum allowed: 600 lines per PR.

Please split your changes into smaller, focused PRs.

Tip: Use --no-verify to bypass this check if necessary.

Now that's a helpful error message! Let's break down why this is so much better:

• Clear and Direct: It immediately states the problem: "PR too large." No ambiguity here.
• Specific Line Count: It tells you exactly how many lines you've changed (644 in this example) and how many lines were insertions and deletions. This is crucial information for understanding the scope of the changes.
• Line Limit Reminder: It clearly states the maximum allowed line count (600). This reinforces the project's coding guidelines.
• Actionable Advice: It suggests splitting the PR into smaller, focused chunks. This gives the developer a concrete next step.
• Bypass Option: It mentions the --no-verify flag, which allows bypassing the check if necessary (for emergency hotfixes, for example). This is important for flexibility.

Essentially, this error message acts like a mini-tutorial, guiding the developer toward the correct solution. It's like having a friendly code review bot giving you helpful feedback.

The Root Cause: A Generic Error Handler

To understand why we were getting the vague error message, we had to dive into our pre-push hook script, which we call preflight.sh. This script runs a series of checks before allowing code to be pushed, including tests, linting, and, of course, the PR size limit. After investigating, we discovered that the script had a generic error handler. This meant that no matter what went wrong – whether it was a test failure, a linting error, or a PR size violation – the script would simply output the generic "failed to push" message. It was like using a one-size-fits-all bandage for every type of wound! This approach made the script simpler to write initially, but it sacrificed valuable information in the error messages.

The Solution: Specific Error Handling

The fix, therefore, was to implement specific error handling within the preflight.sh script. This meant adding logic to detect the specific cause of the failure and generate a tailored error message. In the case of the PR size limit, we needed to:

1. Calculate the line count: We used Git commands to determine the number of inserted and deleted lines.
2. Check against the limit: We compared the total line count against the 600-line limit.
3. Generate a specific error message: If the limit was exceeded, we displayed the informative error message we described earlier, including the line count, limit, and suggestions for splitting the PR.

This involved adding some conditional logic to the script, but the payoff in terms of improved developer experience was well worth it. It's like upgrading from a rusty old map to a GPS navigation system – you get much clearer directions!

Acceptance Criteria: Ensuring a Clear Message

To ensure we had truly solved the problem, we established a set of acceptance criteria for the fix. These criteria outlined the specific requirements for the error message:

1. Line Count and Limit: The error message must state the exact line count (insertions + deletions) and show the 600-line limit. This is the core information the developer needs.
2. Splitting Suggestion: The error message should suggest splitting the PR into smaller, focused PRs. This provides actionable advice.
3. --no-verify Mention: The error message should mention the --no-verify bypass option. This gives developers an escape hatch when needed.
4. Distinguishable Error: The error should be distinguishable from other pre-push failures (tests, linting, etc.). This prevents confusion and ensures the developer knows the specific cause of the failure.
5. Consider Color-Coding: We also considered using color-coding (red for error, yellow for warning, blue for info) to further enhance the clarity of the error message. Color-coding can make error messages even easier to scan and understand.

By defining these criteria, we had a clear roadmap for testing the fix and ensuring it met our goals. It's like having a checklist for a mission – you want to make sure you've covered all the bases!

Lessons Learned: The Path to Better Error Messages

This experience taught us some valuable lessons about the importance of clear error messages and how to create them:

• Prioritize Specificity: Generic error messages are rarely helpful. Strive to provide as much context as possible about the cause of the error.
• Provide Actionable Advice: Don't just tell the user what went wrong; tell them what they can do about it.
• Consider the User Experience: Error messages are part of the user interface. Design them to be clear, concise, and helpful.
• Test Your Error Handling: Just like you test your code, test your error handling logic to ensure it's working correctly.

By applying these lessons, we can create a more developer-friendly environment and reduce the frustration associated with debugging. It's like building a better bridge – it makes the journey smoother for everyone!

Conclusion: A Win for Developer Productivity

In conclusion, fixing the unclear pre-push error message was a small change with a big impact. By providing developers with more specific and helpful feedback, we've improved their workflow, reduced frustration, and ultimately boosted productivity. Remember, clear error messages are not just a nice-to-have; they're a critical part of a healthy development process. So, the next time you're writing error messages, think about the developer on the receiving end and strive to be as helpful as possible. Your team (and your future self) will thank you for it!