fix: honor user-supplied test.root instead of clobbering it

e2e/case14.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+set -o errexit -o nounset -o pipefail
+
+# Case 14: generate a coverage report when the vitest config sets an explicit
+# test.root. The covered source lives under the root, so include globs must
+# resolve relative to it (no `..` prefix) and coverage must be produced.
+bazel coverage //vitest/tests:case14 --instrument_test_targets
+
+COVERAGE_FILE="bazel-testlogs/vitest/tests/case14/coverage.dat"
+
+if [ ! -f "$COVERAGE_FILE" ]; then
+	echo "Missing coverage file $COVERAGE_FILE"
+	exit 1
+fi
+
+if ! grep -q "SF:vitest/tests/case14/src/case14.index.js" "$COVERAGE_FILE"; then
+	echo "Coverage file does not contain coverage for covered function"
+	exit 1
+fi

vitest/defs.bzl

@@ -68,6 +68,11 @@ def vitest_test(
             minus TypeScript since we this rule extends from the configuration. TypeScript vitest configs should be transpiled
             before being passed to vitest_test with [rules_ts](https://github.com/aspect-build/rules_ts).
 
+            An explicit `test.root` in the config is honored; a relative value is resolved against the config
+            file's directory. When `test.root` is not set it defaults to the target's package directory. Coverage
+            `include` globs are resolved relative to `test.root`, so an explicit root must contain the source files
+            under test.
+
         data: Runtime dependencies of the Vitest test.
 
             This should include all test files, configuration files & files under test.

vitest/private/vitest_config_template.mjs

@@ -17,12 +17,16 @@ const projectRoot = path.join(
 );
 
 
-// Glob pattern paths for which files to cover must be relative to this
-// vitest config file in runfiles.
 const vitestConfigDir = path.dirname(
   _resolveRunfilesPath(generatedConfigShortPath),
 );
 
+// Directory of the user config file, used to resolve a relative explicit
+// `test.root` the way Vitest would (relative to the config file).
+const userConfigDir = userConfigShortPath
+  ? path.dirname(_resolveRunfilesPath(userConfigShortPath))
+  : vitestConfigDir;
+
 function _resolveRunfilesPath(rootpath) {
   return path.join(projectRoot, rootpath);
 }
@@ -67,7 +71,15 @@ if (userConfigShortPath) {
 if (!config.test) {
   config.test = {};
 }
-config.test.root = vitestConfigDir;
+
+// Vitest defaults `test.root` to `process.cwd()`, which under Bazel is the
+// output-tree root rather than the package, so a value must always be set.
+// Default to the generated config's directory, but honor an explicit user
+// `test.root` (a relative one resolved against the user config file, as
+// Vitest would) instead of clobbering it.
+config.test.root = config.test.root
+  ? path.resolve(userConfigDir, config.test.root)
+  : vitestConfigDir;
 
 if (autoConfTestSequencer) {
   if (config.test.sequence) {
@@ -126,13 +138,14 @@ if (coverageEnabled) {
     reporter: ["text", ["lcov", { file: coverageFile, projectRoot }]],
   };
 
-  // Only generate coverage for files declared in the COVERAGE_MANIFEST
+  // Glob pattern paths for which files to cover must be relative to test.root,
+  // which Vitest resolves coverage include globs against.
   config.test.coverage.include = fs
       .readFileSync(process.env.COVERAGE_MANIFEST)
       .toString("utf8")
       .split("\n")
       .filter((f) => f !== "")
-      .map((f) => path.relative(vitestConfigDir, path.join(projectRoot, f)));
+      .map((f) => path.relative(config.test.root, path.join(projectRoot, f)));
 }
 
 if (process.env.JS_BINARY__LOG_DEBUG) {

vitest/tests/BUILD.bazel

@@ -173,3 +173,27 @@ vitest_test(
     ],
     node_modules = "//:node_modules",
 )
+
+# Case 13: an explicit relative test.root must be honored and resolved against
+# the config file's directory, not clobbered by the package directory.
+vitest_test(
+    name = "case13",
+    config = "case13/case13.vitest.config.mjs",
+    data = [
+        "case13/case13.test.js",
+        "case13/src/case13.setup.js",
+    ],
+    node_modules = "//:node_modules",
+)
+
+# Case 14: coverage with an explicit test.root (see e2e test); the covered
+# source lives under the root, so include globs must resolve relative to it.
+vitest_test(
+    name = "case14",
+    config = "case14/case14.vitest.config.mjs",
+    data = [
+        "case14/src/case14.index.js",
+        "case14/src/case14.test.js",
+    ],
+    node_modules = "//:node_modules",
+)

vitest/tests/case13/case13.test.js

@@ -0,0 +1,5 @@
+import { test, expect } from "vitest";
+
+test("explicit relative test.root is honored", () => {
+  expect(globalThis.__CASE13_ROOT__).toBe("src");
+});

vitest/tests/case13/case13.vitest.config.mjs

@@ -0,0 +1,11 @@
+import { defineConfig } from "vitest/config";
+
+// Explicit relative test.root: must be honored and resolved against this config
+// file's directory, so setupFiles below resolves under src/.
+export default defineConfig({
+  test: {
+    environment: "node",
+    root: "./src",
+    setupFiles: ["./case13.setup.js"],
+  },
+});

vitest/tests/case13/src/case13.setup.js

@@ -0,0 +1 @@
+globalThis.__CASE13_ROOT__ = "src";

vitest/tests/case14/case14.vitest.config.mjs

@@ -0,0 +1,10 @@
+import { defineConfig } from "vitest/config";
+
+// Coverage combined with an explicit test.root: the covered source lives under
+// the root, so include globs must resolve relative to it without a `..` prefix.
+export default defineConfig({
+  test: {
+    environment: "node",
+    root: "./src",
+  },
+});

vitest/tests/case14/src/case14.index.js

@@ -0,0 +1,5 @@
+function covered() {
+  return "covered";
+}
+
+exports.covered = covered;

vitest/tests/case14/src/case14.test.js

@@ -0,0 +1,6 @@
+const { test, expect } = await import("vitest");
+const { covered } = require("./case14.index.js");
+
+test("covered", () => {
+  expect(covered()).toEqual("covered");
+});