Debug node test coverage failures. Use when ./tools/test-js-with-node --coverage reports lines missing coverage.
When ./tools/test-js-with-node --coverage fails with lines missing
coverage, follow this process.
The error looks like:
ERROR: web/src/filter.ts no longer has complete node test coverage
Lines missing coverage: 90, 225, 1780
This means the listed lines in the source file were never executed by
any test. Zulip enforces 100% line coverage for all files not listed
in EXEMPT_FILES in tools/test-js-with-node.
Read the source file at the reported line numbers. Classify each uncovered line:
assert(false, ...)COVERAGE_EXCLUDE_LINEStools/test-js-with-node// istanbul ignore next comments. Use sparingly.Tests for web/src/foo.ts live in web/tests/foo.test.cjs. Read the
test file to understand existing patterns before adding new tests.
The common predicate test pattern:
const predicate = get_predicate([["operator", operand]]);
assert.ok(predicate({...message that should match...}));
assert.ok(!predicate({...message that should not match...}));
Add tests near related existing tests. Follow the existing style exactly. Tests should exercise the behavior, not the implementation detail — name and locate tests based on what they verify, not which internal code path they hit.
Use // istanbul ignore next where appropriate, being sure that
you think the codebase is better without test coverage for this case.
./tools/test-js-with-node --coverage
This runs all JS tests in serial mode with istanbul/nyc instrumentation and checks that non-exempt files have 100% line coverage.
For faster iteration, you can run an individual test and analyze the coverage output files to see whether it covered a target line.
tools/test-js-with-node — Test runner, coverage enforcement,
EXEMPT_FILES list, COVERAGE_EXCLUDE_LINES patternstools/coveragerc — Python equivalent (for reference on pattern
style)web/tests/*.test.cjs — All JS test filesvar/node-coverage/ — Generated coverage reports (HTML viewable
at http://zulipdev.com:9991/node-coverage/index.html), but
you can also access in var/node-coverage/.