feat: improve testing framework and add CI

[simonmysun]

Resolves #33

[Copilot]

Pull request overview

This PR makes the Bash-based test suite self-checking (assertions + deterministic offline fixtures) and adds GitHub Actions CI to run ShellCheck and the suite across supported Bash versions.

Changes:

• Introduces a tiny assertion helper (tests/assert.sh) and converts existing tests into self-checking unit/E2E scripts.
• Refactors the test entrypoint to auto-discover *.test.sh unit tests and explicitly run E2E tests.
• Adds a CI workflow to run ShellCheck and the test suite in bash:4.1 and bash:5.2, and updates docs + attributes accordingly.

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tests/templating.sh	Converts templating checks into deterministic, self-checking assertions using ell_echo.
tests/redaction.sh	Removes legacy non-asserting redaction script (replaced by plugin unit test).
tests/piping.sh	Removes legacy piping script (replaced by helpers/piping.test.sh).
tests/parse_output.sh	Adds self-checking parsing tests using file:// fixtures and a helper runner.
tests/logging.sh	Removes legacy logging script (replaced by helpers/logging.test.sh).
tests/entry.sh	Makes suite runnable from any checkout path; auto-discovers unit tests and runs E2E tests.
tests/docker.sh	Runs the suite in both bash container versions and propagates combined status.
tests/assert.sh	Adds new assertion library used by unit/E2E tests.
README.md	Documents the new test layout, local/Docker usage, and CI behavior.
plugins/redaction/50_post_input.test.sh	Adds unit tests for redaction plugin, asserting secrets are removed and markers inserted.
helpers/render_to_text.test.sh	Fixes the awk script path now that the test is co-located in helpers/.
helpers/piping.test.sh	Adds unit tests for helpers/piping.sh.
helpers/logging.test.sh	Adds unit tests for helpers/logging.sh including stderr-only guarantees.
helpers/json.test.sh	Adds unit tests for the pure-bash JSON parser (paths, escapes, unicode, validity).
.github/workflows/ci.yml	Adds CI: ShellCheck (errors blocking, warnings non-blocking) + test matrix across bash versions.
.gitattributes	Ensures consistent LF endings for workflow YAML files.

Comments suppressed due to low confidence (1)

tests/assert.sh:88

• assert_not_contains has the same glob-pattern issue as assert_contains: needles containing characters like '[' are treated as patterns rather than literal substrings. This can cause false failures/passes (e.g. redaction marker checks). Escape glob metacharacters in the needle before matching.

# assert_not_contains <name> <haystack> <needle>
# Succeeds if <haystack> does NOT contain the literal substring <needle>.
# Useful for security assertions: "the secret must not survive".
assert_not_contains() {
  local name="${1}" haystack="${2}" needle="${3}";
  case "${haystack}" in
    *"${needle}"*)

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[Copilot]

Pull request overview

Copilot reviewed 16 out of 17 changed files in this pull request and generated 3 comments.