minimise

name	minimise
description	Prune a bug fix or new tests down to the smallest correct diff through multiple elimination passes. Use before committing any fix or test addition.

Minimise

The goal is to remove every line that is not strictly required for correctness, then verify the result still passes the relevant tests.

Process

Repeat the following until no further reductions are possible:

1. Read the diff. Run git diff HEAD (or git diff --cached if staged) and read every changed file in full.

2. Challenge each change. For every changed line ask:

   • Would removing this line cause a test to fail or a bug to reappear?
   • Is this a cleanup, rename, refactor, or comment that is not load-bearing?
   • For new tests: does an existing test already cover this behaviour? If so, drop the new test entirely.

3. Remove non-essential changes. Delete anything that does not answer "yes" to the first question above. Prefer shrinking an existing case over adding a new one.

4. Run the focused tests. Test files live in test/test_*.jl and are all included by test/runtests.jl. A single file can be run with the shared preamble from runtests.jl:

   julia --project -e '
   using Test, DomainSets, FEMTools, SparseArrays, StaticArrays
   using DomainSets: ×
   const FP64 = Float64; const FP32 = Float32
   include("test/test_mesh.jl")'
   

   Run the full suite (julia --project -e "using Pkg; Pkg.test()") before the final report. Confirm all tests pass before continuing.

5. Repeat from step 1 until a full pass produces no further removals.

Heuristics

• A one-line fix is better than a five-line fix.
• A new test case added to an existing @testset is better than a new @testset.
• Comments and blank lines added alongside a fix are not load-bearing; remove them unless they explain something non-obvious.
• Helper functions introduced solely for the fix are a red flag; inline them.
• Changes to examples/ are demos, not library code: keep them out of a src/ bug-fix diff unless the example is the regression test.

When to stop

Stop when every remaining line answers "yes" to: if I remove this, the targeted bug reappears or the targeted test fails. At that point report the final diff and suggest committing.