Centralized test result descriptions across 157 test cases, replacing ad-hoc assertions with shared vocabulary. Tests now read like documentation, and failures explain what broke in business terms, not XML structures.

Commit: 7afd857

Why this is October’s standout

When projects are maintained by one person and used sporadically inside big companies, tests are not only a safety net—they are one of the main ways new contributors learn how the system behaves. In October 2023 I generalized the string‑based description of test results to increase readability and intent. It sounds small, but the impact is real: reviewers understand failures faster, contributors spend less time deciphering assertion details, and future me can triage a red CI job without mentally reconstructing the expected state from raw object graphs.

Tests often fail “usefully” when the failure message explains what the system intended to do in domain words, not in low‑level structures. Instead of a brittle dump of runs, fields, and comment markers, a generalized description routine can say: “expected one placeholder replaced in paragraph 3, found none,” or “expected no comment ranges in SDT X, found 1.” That is a better conversation starter in code reviews and issue triage.

What actually changed

  • Unified test data model by removing duplicate context classes (Name.java, NamesContext.java) and consolidating them into a single Contexts.names() factory method that returns inline records—less boilerplate, more focus on test intent.

  • Rewrote 3 major test files (DefaultTests.java, MultiStampTest.java, test utilities) to use the generalized stampAndLoadAndExtract() pattern, replacing 50+ lines of manual DOM traversal and brittle cell-content assertions with simple string equality.

  • Standardized assertion format across 157 parameterized tests using arguments() instead of of(), ensuring consistent parameter naming and making test data more scannable.

  • Converted DOM inspection to domain assertions in MultiStampTest: instead of counting table rows and cells, the test now compares a readable multi-line string showing the exact expected document structure—failures highlight the semantic delta, not XML noise.

  • Improved code formatting in RepeatDocPartProcessor.java (254 line changes, mostly indentation consistency) to match the rest of the codebase, making future diffs cleaner.

These improvements make tests read like documentation‑as‑code. When someone opens a test to understand how Paragraph.replace behaves or how comments are removed from SdtRun, the narrative is easier to follow. It also helps keep PRs focused: when assertion messages are clear, reviewers can debate intent rather than re‑derive it from low‑level details.

Example transformation:

// Before: brittle DOM traversal
assertRowContainsText(tableRows.get(0), "Homer");
assertTrue(cellContent.contains(text), 
    String.format("'%s' is not in '%s'", text, cellContent));

// After: readable narrative assertion
assertEquals("""
    This table row should be expanded to multiple rows: Homer.
    This table row should be expanded to multiple rows: Marge.
    ...""", stamper.stampAndLoadAndExtract(template, context));

Agile and craftsmanship lens

  • Optimize for feedback clarity. A crisp failure message is a rapid feedback loop; it tells you what to fix and where. The new format shows expected vs actual as readable paragraphs, not object graphs.
  • DRY the narrative. A single description engine (stampAndLoadAndExtract()) avoids tiny divergences across tests that confuse future readers. The 157 test cases now share one vocabulary.
  • Test as teaching. When tests read like a short story about the behavior, they onboard contributors and document design. The MultiStampTest example now shows exactly what multi-stamping produces.
  • Reduce test maintenance tax. By centralizing context creation (Contexts.names()) and output formatting, test refactoring becomes surgical—change one method, fix all 157 tests.

Solo‑maintainer + enterprise usage angle

As the sole maintainer, I rely on tests to double as living documentation. When an enterprise team reports a bug, I often encode their scenario as a fixture and a test. If that test’s failure explains the mismatch in domain terms, we can align faster—sometimes asynchronously, without meetings. For contributors dropping in every few months, a consistent assertion vocabulary lowers cognitive load: they can pattern‑match on familiar phrasing and focus on the change at hand.

The MultiStampTest rewrite is a perfect example: the old version required understanding DOCX4J’s Tbl, Tr, Tc hierarchy and TextUtils.getText() semantics. The new version just shows the expected document as a readable string—anyone can verify correctness without DOCX4J knowledge.

Risks and mitigations

  • Risk: Over‑abstracting failure details loses debugging context
    Mitigation: The stampAndLoadAndExtract() output includes formatting markers (like ❬text❘properties❭) that preserve structural information while staying human-readable. Deep debugging can still inspect the raw WordprocessingMLPackage.

  • Risk: Description drift vs. code—test assertions claim behavior X but implementation does Y.
    Mitigation: Descriptions are built from the same domain primitives the engine uses (DocumentUtil, paragraph extraction), so they evolve together. The 157 parameterized tests act as a regression suite.

  • Risk: Hard‑to‑read diffs when tests fail.
    Mitigation: Multi-line strings with consistent structure (one paragraph per line) produce line-by-line diffs highlighting which paragraph changed.

  • Risk: Test data duplication when multiple tests need similar contexts.
    Mitigation: The Contexts factory class centralizes creation patterns (names(), role(), empty()), making test setup DRY and discoverable.

How to apply this in your project

  1. Write a “result description” helper that takes your domain objects and renders meaningful summaries. For DOCX, this meant extracting text + formatting markers; for your domain, it might be JSON schemas, HTTP response shapes, or state machine transitions.
  2. Replace bespoke assertion messages with calls to this helper across your test suite. Start with your most-changed tests to prove value, then refactor systematically.
  3. Consolidate test data builders into a single factory class (like Contexts). This reduces duplication and makes test setup patterns discoverable.
  4. Standardize your test structure: use the same test method signature, parameter order, and naming conventions. The 157-test suite uses (name, config, context, template, expected) everywhere—muscle memory for readers.
  5. Include example failure messages in your docs so contributors know what to expect from CI. Show the before (raw object graph) and after (domain narrative) to illustrate the value.

References

  • Commit: 7afd857
  • Test suite refactoring: DefaultTests.java (157 parameterized tests), MultiStampTest.java (DOM→string conversion)
  • Context consolidation: removed Name.java, NamesContext.java; added Contexts.names() factory
  • Related commits: tightening test setup and generalized descriptions around 2023‑10‑16 and 2023‑10‑25.