Module: DevDoc::Test::Lints::DuplicateSnapshot

Defined in:
lib/dev_doc/test/lints/duplicate_snapshot.rb

Overview

Reject byte-identical controller-test snapshots within the same *_results dir.

Rationale

"Test quality" is normally subjective. Two tests serializing the exact same rendered response is an objective, computable proxy for a redundant or weak test. When response_assert_equal snapshots collide, it's almost always one of:

1. **Same scenario tested twice** — should be one test with the
 combined assertions.
2. **Fixtures don't exercise the difference** — the test claims to
 verify behaviour X, but the inputs all collapse to the same
 rendered state, so it passes without actually testing X. (The
 most dangerous case — green but vacuous.)
3. **A negative/absence assertion** — a test for "X is NOT shown"
 legitimately renders identically to the baseline. This is the
 one *correct* duplicate; acknowledge it with the inline marker.

Aggressive by design: a false positive costs only a quick review and one inline comment, while a silent duplicate hides a real (1) or (2).

Inline opt-out (NOT a central allow-list)

The justification lives next to the test, so it can't rot or detach. Mark EACH test in an intentionally-duplicate group with # allow_duplicate_snapshot: <reason> — either as a trailing comment on its test '...' do line, or on the comment line directly above it (use the latter when the test line is already long):

test 'index hides the banner' do # allow_duplicate_snapshot: renders like the baseline
...
end

# allow_duplicate_snapshot: renders like the baseline
test 'index hides the banner for a guest who is not in any of the groups' do
...
end

Usage

class DuplicateSnapshotTest < ActiveSupport::TestCase include DevDoc::Test::Lints::DuplicateSnapshot # SNAPSHOT_RESULTS_ROOT = 'test/requests' # override if needed end

Instance Method Summary collapse

Instance Method Details

#test_no_unjustified_duplicate_snapshots ⇒ Object 



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# File 'lib/dev_doc/test/lints/duplicate_snapshot.rb', line 169

def test_no_unjustified_duplicate_snapshots
  result = DuplicateSnapshotChecker.new(snapshot_results_root).offenders
  if result == DuplicateSnapshotChecker::MissingDir
    skip "no snapshot result dirs under #{snapshot_results_root}"
  end

  assert result.empty?, failure_message(result)
end