facebookarchive/prepack

Enhance serializer tests with automated heap traversals

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#1,852 opened on May 3, 2018

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enhancementhelp wantedserializertest needed

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Description

Currently, the serializer tests only checks a heap projection: whatever the inspect function computes.

This is great for debugging issues, as each serializer test tends to be minimal and test a separate feature.

However, we are ignoring additional potential. What could be done is effectively synthesizing an alternative inspect function implementation that returns the result of a systematic, deterministic heap traversal.

Challenges:

  1. Ideally, we'd like to detect any changes to built-ins as well as changes rooted in the global object.
  2. Prepack does not preserve everything, e.g. function names and function source code change. So this should be abstracted by the traversal.
  3. Functions are interesting in general: How can we detect that their behavior didn't change? To start with, we can just ignore that and focus on the immediately accessible heap. Maybe some annotations are needed on how to invoke functions to get interesting outputs, which in turn can be traversed.

Contributor guide

Research direction
Study the existing serializer tests and the inspect function implementation. Design a systematic heap traversal that abstracts changes not preserved by Prepack and detects changes to built ins and global objects. Consider how to represent function outputs.
Tech stack
javascript
Domain
backendbuild system
Issue type
Test
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Needs investigation
Prerequisites
JavaScripttesting
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30