test(oxfmt): Misc refactors (#21484)

- Simplify sort_imports test
- Add note comment to stdin_pipe test
- Update AGENTS.md

Author: leaysgur

apps/oxfmt/AGENTS.md

@@ -80,22 +80,35 @@ npx prettier --config=fmt.json <file>
 
 ## Test Organization (`test/` directory)
 
-Tests are organized by domain and colocated with strict structural rules.
-
-- 1:1:1 Rule: Each test directory contains exactly
-  - 1 test file (`*.test.ts` with the same name with directory)
-  - 0 or 1 `fixtures/` directory (if needed)
-  - Snapshots are colocated automatically by Vitest
-- No Upward References (except `utils.ts` and `oxfmt` binary)
-  - Test files may only reference:
-    - Files within their own directory
-    - Shared `utils.ts` in parent directories
-
-When adding new tests:
-
-- Place test in the appropriate domain directory
-- If the test needs fixtures, create a `fixtures/` subdirectory
-- If multiple test cases share a fixture structure, use subdirectories within `fixtures/` (e.g., `fixtures/basic/`, `fixtures/nested/`)
+Tests are organized into specific domains, each with its own structure.
+
+### `test/api/`: Formatting result tests
+
+Focuses on verifying formatting output. Use the Node.js API. No fixtures, test inputs are inline in each test file.
+
+- Multiple `*.test.ts` files coexist in a flat directory (no subdirectories)
+- Snapshots are colocated in `__snapshots__/` by Vitest
+
+### `test/cli/`: CLI fixture-driven tests
+
+A single `cli.test.ts` auto-discovers and runs all fixture directories via `utils.ts`.
+
+- Each fixture directory contains:
+  - `options.json` — array of test cases (args, cwd, env, stdin, etc.)
+  - `fixtures/` — input files for the test cases
+  - `*.snap.md` — file snapshots (one per test case, named `0.snap.md`, `1.snap.md`, …)
+- Adding a new CLI test: create a new directory with `options.json` and `fixtures/`, then run the test to generate snapshots
+- If exceptional test cases are required, place a separate `*.test.ts` file for them
+
+### `test/lsp/`: LSP integration tests
+
+Each test directory follows the 1:1:1 rule:
+
+- 1 test file (`*.test.ts` with the same name as the directory)
+- 0 or 1 `fixtures/` directory
+- Snapshots are colocated in `__snapshots__/` by Vitest
+
+Shared helpers are in `utils.ts` at the `test/lsp/` level.
 
 ## After updating `Oxfmtrc` (Under `src/core/oxfmtrc`)
 

apps/oxfmt/test/cli/sort_imports/0.snap.md

@@ -2,18 +2,16 @@
 
 ## Command
 ```
-oxfmt --check input.ts
+oxfmt --check --config custom_groups.json custom_groups.ts
 ```
 
 ## File tree
 ```
-- fixtures/
-  - custom_groups/ <CWD>
-    - .oxfmtrc.json
-    - input.ts
-  - custom_groups_selector_modifiers/
-    - .oxfmtrc.json
-    - input.ts
+- fixtures/ <CWD>
+  - custom_groups_selector_modifiers.json
+  - custom_groups_selector_modifiers.ts
+  - custom_groups.json
+  - custom_groups.ts
 ```
 
 # Result

apps/oxfmt/test/cli/sort_imports/1.snap.md

@@ -2,18 +2,16 @@
 
 ## Command
 ```
-oxfmt --check input.ts
+oxfmt --check --config custom_groups_selector_modifiers.json custom_groups_selector_modifiers.ts
 ```
 
 ## File tree
 ```
-- fixtures/
-  - custom_groups/
-    - .oxfmtrc.json
-    - input.ts
-  - custom_groups_selector_modifiers/ <CWD>
-    - .oxfmtrc.json
-    - input.ts
+- fixtures/ <CWD>
+  - custom_groups_selector_modifiers.json
+  - custom_groups_selector_modifiers.ts
+  - custom_groups.json
+  - custom_groups.ts
 ```
 
 # Result

…rts/fixtures/custom_groups/.oxfmtrc.json …sort_imports/fixtures/custom_groups.jsonapps/oxfmt/test/cli/sort_imports/fixtures/custom_groups/.oxfmtrc.json renamed to apps/oxfmt/test/cli/sort_imports/fixtures/custom_groups.json apps/oxfmt/test/cli/sort_imports/fixtures/custom_groups/.oxfmtrc.json renamed to apps/oxfmt/test/cli/sort_imports/fixtures/custom_groups.json

@@ -1,4 +1,11 @@
 [
-  { "cwd": "custom_groups", "args": ["--check", "input.ts"] },
-  { "cwd": "custom_groups_selector_modifiers", "args": ["--check", "input.ts"] }
+  { "args": ["--check", "--config", "custom_groups.json", "custom_groups.ts"] },
+  {
+    "args": [
+      "--check",
+      "--config",
+      "custom_groups_selector_modifiers.json",
+      "custom_groups_selector_modifiers.ts"
+    ]
+  }
 ]

…_imports/fixtures/custom_groups/input.ts …i/sort_imports/fixtures/custom_groups.tsapps/oxfmt/test/cli/sort_imports/fixtures/custom_groups/input.ts renamed to apps/oxfmt/test/cli/sort_imports/fixtures/custom_groups.ts apps/oxfmt/test/cli/sort_imports/fixtures/custom_groups/input.ts renamed to apps/oxfmt/test/cli/sort_imports/fixtures/custom_groups.ts

@@ -7,6 +7,9 @@ const FIXTURE = join(import.meta.dirname, "fixtures", "parser.ts");
 
 // https://github.com/oxc-project/oxc/issues/17939
 describe("stdin pipe", () => {
+  // NOTE: This test uses Unix commands (`cat`, `wc`) via shell pipes.
+  // On our Windows CI (GitHub Actions), these resolve from Git for Windows in PATH.
+  // May fail on some Windows environments without Unix tools in PATH.
   it("should not report WouldBlock error on large file piped to wc", async () => {
     const cmd = `cat "${FIXTURE}" | node "${CLI_PATH}" --stdin-filepath=parser.ts | wc -l`;
     const result = await execa({ shell: true, reject: false })`${cmd}`;