# Migrate Junit Source To Tabletest

> Convert JUnit 5 @MethodSource/@CsvSource/@ValueSource parameterized tests to @TableTest (JDK8)

- Skill: `datadog/migrate-junit-source-to-tabletest` (Agent Skill)
- Install (CLI): `npx skillmds@latest add datadog/migrate-junit-source-to-tabletest`
- Raw SKILL.md: https://api.skillmd.com/api/skills/datadog/migrate-junit-source-to-tabletest/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: datadog (https://skillmd.com/u/datadog)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/datadog/migrate-junit-source-to-tabletest

---

Goal: Migrate JUnit 5 parameterized tests using @MethodSource/@CsvSource/@ValueSource to @TableTest with minimal churn and passing tests.

Process (do in this order):
1) Locate targets via Grep (no agent subprocess). Search for: "@ParameterizedTest", "@MethodSource", "@CsvSource", "@ValueSource".
2) Read all matching files up front (parallel is OK).
3) Convert eligible tests to @TableTest.
4) Write each modified file once in full using Write (no incremental per-test edits).
5) Run module tests once and verify "BUILD SUCCESSFUL". If failed, inspect JUnit XML report.

Import: `import org.tabletest.junit.TableTest;`

JDK 8 rules:
- No text blocks.
- @TableTest must use String[] annotation array syntax:
  ```
  @TableTest({
   "a | b",
   "1 | 2"
  })
  ```

Table formatting rules (mandatory):
- Always include a header row (parameter names).
- Always add a "scenario" column; using common sense for naming; scenario is NOT a method parameter.
- Use '|' as delimiter.
- Align columns with spaces so pipes line up vertically.
- Prefer single quotes for strings requiring quotes (e.g., 'a|b', '[]', '{}', ' ').
- Use value sets (`{a, b, c}`) instead of matrix-style repetition when only one dimension varies across otherwise-identical rows.

Conversions:
A) @CsvSource
- Remove @ParameterizedTest and @CsvSource.
- If delimiter is '|': rows map directly to @TableTest.
- If delimiter is ',' (default): replace ',' with '|' in rows.

B) @ValueSource
- Keep single-parameter tests on `@ValueSource` (and `@NullSource` when null cases are needed).
- Otherwise convert to @TableTest with header from parameter name.
- Each value becomes one row.
- Add "scenario" column using common sense for name.

C) @MethodSource (convert only if values are representable as strings)
- Convert when argument values are primitives, strings, enums, booleans, nulls, and simple collection literals supported by TableTest:
  - Array: [a, b, ...]
  - List: [a, b, ...]
  - Set: {a, b, ...}
  - Map: [k: v, ...]
- `@TableTest` and `@MethodSource` may be combined on the same `@ParameterizedTest` when most cases are tabular but a few cases require programmatic setup.
- In combined mode, keep table-friendly cases in `@TableTest`, and put only non-tabular/complex cases in `@MethodSource`.
- If `@TableTest` is not viable for the test at all, use `@MethodSource` only.
- For `@MethodSource`, name the arguments method `<testMethodName>Arguments` (camelCase, e.g. `testMethodArguments`) and return `Stream<Arguments>` using `Stream.of(...)` and `arguments(...)` with static import.
- Blank cell = null (non-primitive).
- '' = empty string.
- For String params that start with '[' or '{', quote to avoid collection parsing (prefer '[]'/'{}').

D) @TypeConverter
- Use `@TypeConverter` for symbolic constants used by migrated table rows (e.g. `Long.MAX_VALUE`, `DDSpanId.MAX`).
- Prefer explicit one-case-one-return mappings.
- Prefer shared converter utilities (e.g. in `utils/test-utils`) when reuse across modules is likely.

Scenario handling:
- If MethodSource includes a leading description string OR @ParameterizedTest(name=...) uses {0}, convert that to a scenario column and remove that parameter from method signature.

Cleanup:
- Delete now-unused @MethodSource provider methods and unused imports.

Mixed eligibility:
- Prefer combining `@TableTest` + `@MethodSource` on one `@ParameterizedTest` when only some cases are complex.

Do NOT convert when:
- Most rows require complex builders/mocks.

Test command (exact):
./gradlew :path:to:module:test --rerun-tasks 2>&1 | tail -20
- If BUILD FAILED: cat path/to/module/build/test-results/test/TEST-*.xml