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Shell Tool Testing

Shell Tool Testing

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The `prove` command and Test Anything Protocol (TAP) offer a lightweight, language-agnostic way to test Unix shell tools without heavy frameworks, simplifying test suite management.
What: Stefan `st` Kottwitz advocates for `prove` (from the Perl ecosystem) and TAP for testing shell tools, similar to Python's `unittest`. TAP is a plain-text format for test results, and `prove` discovers, runs, and summarizes tests. A small shared `common.sh` harness can manage temporary directories (`mktemp -d`), provide `report_ok`/`report_not_ok` functions for automated test numbering, and handle cleanup (`rm -rf`), making shell test suites easy to grow while keeping failures readable.
Why it matters: This approach democratizes automated testing for shell scripts, removing the barrier of complex frameworks and dependencies. By using widely available tools and a simple, human-readable protocol, it encourages more robust development practices for command-line utilities and system automation.
Takeaway: When developing shell scripts or Unix tools, consider using `prove` with TAP for lightweight, readable, and easy-to-manage automated testing.
Deep dive
  • Automated testing is crucial for shell tools and Kakoune plugins.
  • Many shell script test harnesses exist, but often require third-party libraries.
  • prove command (from Perl ecosystem) is a language-agnostic test runner.
  • prove is similar to Python's unittest but works with any language outputting TAP.
  • Test Anything Protocol (TAP) is a plain-text, human-readable format for test results (e.g., ok N - description, not ok N - description).
  • TAP includes TAP version X and 1..N (total tests expected).
  • By default, prove looks for t/*.t files; can be configured via .proverc to use --ext test for t/*.test files.
  • Tests should be isolated using temporary directories created with mktemp -d and cleaned up with rm -rf.
  • A shared common.sh script can provide helper functions like report_ok and report_not_ok to automate test numbering and TAP output.
  • common.sh can also handle bailouts (stopping on first failure), strict mode checks, and capturing stdout/stderr.
Decoder
  • prove: A command-line utility from the Perl ecosystem used to discover, run, and summarize test results in various formats, notably TAP.
  • Test Anything Protocol (TAP): A simple, human-readable, line-based text format for reporting test results, commonly used for automated testing.
  • mktemp -d: A Unix command that securely creates a unique temporary directory.
  • common.sh: A common practice in shell scripting for a shared script to include reusable functions and setup for a test suite.
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