rust-lang / rust-lang/rust

`assert_eq!` should show a diff for failing asserts

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#145,114 2 comments 1 reaction 0 assignees View on GitHub

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C-feature-request T-libs
Dominant language
Rust
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Description

Problem

When an assert_eq! in a test fails, the differences between left and right are very hard to see.

Proposed Solution

cargo test should show a diff, when an assert_eq! fails.

Notes

No response

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing a failing assert_eq! with cargo test and trace how the failure output is produced. Identify the relevant implementation and tests in the Rust repository; the work is done when failing equality assertions show a useful diff without regressing existing test output.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
testing-qa
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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