fix(rees): run REES coverage's test child from review-enrichment/ (#8616)

spawnSync ran c8 and the node:test child it wraps with the same cwd
(the monorepo root), needed so c8's lcov SF: paths remap to
review-enrichment/src/** for Codecov. But that left the actual test
process running from the wrong directory, so tests that read fixtures
via bare relative paths (e.g. analyzer-metadata.test.ts reading
"analyzer-metadata.json") failed with ENOENT even though the fixture
exists at review-enrichment/analyzer-metadata.json.

Preload a small --require script into only the spawned test child to
chdir it into review-enrichment/ before node:test loads any files,
leaving c8's own process cwd (and therefore its SF: path remapping)
untouched. Test file arguments switch from root-relative to absolute
paths since they're now resolved from a different cwd.

Author: JSONbored

scripts/rees-coverage-chdir.cjs

@@ -0,0 +1,8 @@
+// Preloaded via --require before node:test loads review-enrichment's test files.
+// c8 (the parent process) must keep its own cwd at the monorepo root so lcov SF: paths
+// remap to `review-enrichment/src/**` for Codecov (#6250); this only chdir's the spawned
+// test child, so tests that read fixtures with bare relative paths (e.g. "analyzer-metadata.json")
+// resolve them against review-enrichment/, matching `npm run test:node`.
+const { join } = require("node:path");
+
+process.chdir(join(__dirname, "..", "review-enrichment"));

scripts/rees-coverage.ts

@@ -3,7 +3,7 @@
 // (not bare `src/**`), and expands the test list in-process so Windows/npm quoting cannot drop the suite.
 import { spawnSync } from "node:child_process";
 import { readFileSync, readdirSync, writeFileSync } from "node:fs";
-import { join, relative } from "node:path";
+import { join } from "node:path";
 import { fileURLToPath, URL } from "node:url";
 
 /** Normalize c8's SF: paths to forward slashes for Codecov. Swallows only a missing report
@@ -39,8 +39,10 @@ function main() {
   const c8Bin = join(root, "review-enrichment", "node_modules", "c8", "bin", "c8.js");
   const reportDir = join(root, "review-enrichment", "coverage");
   const testRoot = join(root, "review-enrichment", "test");
+  const chdirPreload = join(root, "scripts", "rees-coverage-chdir.cjs");
 
-  const tests = collectTests(testRoot).map((path) => relative(root, path).split("\\").join("/"));
+  // Absolute paths: the test child's cwd is review-enrichment/ (see chdirPreload), not root.
+  const tests = collectTests(testRoot).map((path) => path.split("\\").join("/"));
   if (tests.length === 0) {
     console.error("rees-coverage: no review-enrichment/test/**/*.test.ts files found");
     process.exit(1);
@@ -57,6 +59,8 @@ function main() {
       "--exclude=**/*.d.ts",
       "--all",
       process.execPath,
+      "--require",
+      chdirPreload,
       "--test",
       "--experimental-strip-types",
       ...tests,