feat: add bats tests, docs (#139)

* fix(test): ensure bats file list uses xargs

* docs(readme): use yarn for testing instructions

* fix(test): ensure pipelines fail properly

* docs(alias): fix table header

---------

Signed-off-by: Ismo Vuorinen <ismo@ivuorinen.net>

test-all.sh

@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+# Run all bats tests
+
+set -euo pipefail
+
+if [ -x "node_modules/bats/bin/bats" ]; then
+  git ls-files '*.bats' -z | xargs -0 node_modules/bats/bin/bats
+elif command -v npx >/dev/null; then
+  git ls-files '*.bats' -z | xargs -0 npx --yes bats
+elif command -v bats >/dev/null; then
+  git ls-files '*.bats' -z | xargs -0 bats
+else
+  echo "bats not installed. Run 'yarn install' first." >&2
+  exit 1
+fi