Resolve .browserslistrc as a project-wide file (#13028)

packages/babel-core/src/config/partial.js

@@ -126,7 +126,7 @@ export default function* loadPrivatePartialConfig(
 
   const options: NormalizedOptions = {
     ...merged,
-    targets: resolveTargets(merged, absoluteRootDir, filename),
+    targets: resolveTargets(merged, absoluteRootDir, absoluteRootDir),
 
     // Tack the passes onto the object itself so that, if this object is
     // passed back to Babel a second time, it will be in the right structure

packages/babel-core/src/config/resolve-targets-browser.js

@@ -8,7 +8,7 @@ export function resolveTargets(
   // eslint-disable-next-line no-unused-vars
   root: string,
   // eslint-disable-next-line no-unused-vars
-  filename: string | void,
+  configFilePath: string | void,
 ): Targets {
   let { targets } = options;
   if (typeof targets === "string" || Array.isArray(targets)) {

packages/babel-core/src/config/resolve-targets.js

@@ -14,7 +14,7 @@ import getTargets, { type Targets } from "@babel/helper-compilation-targets";
 export function resolveTargets(
   options: ValidatedOptions,
   root: string,
-  filename: string | void,
+  configFilePath: string = root,
 ): Targets {
   let { targets } = options;
   if (typeof targets === "string" || Array.isArray(targets)) {
@@ -27,13 +27,13 @@ export function resolveTargets(
 
   let configFile;
   if (typeof options.browserslistConfigFile === "string") {
-    configFile = path.resolve(root, options.browserslistConfigFile);
+    configFile = path.resolve(configFilePath, options.browserslistConfigFile);
   }
 
   return getTargets((targets: any), {
     ignoreBrowserslistConfig: options.browserslistConfigFile === false,
     configFile,
-    configPath: filename ?? root,
+    configPath: root,
     browserslistEnv: options.browserslistEnv,
   });
 }

packages/babel-core/test/fixtures/targets/node_modules/dep/.babelrc.json

@@ -0,0 +1,3 @@
+{
+	"browserslistConfigFile": "./.browserslistrc"
+}

packages/babel-core/test/targets.js

@@ -91,11 +91,24 @@ describe("browserslist", () => {
     ).toEqual({ chrome: "80.0.0" });
   });
 
-  it("loads .browserslistrc relative to the input file", () => {
+  it("loads .browserslistrc relative to the root", () => {
     expect(
       loadOptions({
         cwd: join(cwd, "fixtures", "targets"),
-        filename: "./nested/test.js",
+        filename: "./node_modules/dep/test.js",
+      }).targets,
+    ).toEqual({ chrome: "80.0.0" });
+  });
+
+  // TODO: browserslistConfig is currently resolved starting from the root
+  // rather than from the config file.
+  // eslint-disable-next-line jest/no-disabled-tests
+  it.skip("loads nested .browserslistrc files if explicitly specified", () => {
+    expect(
+      loadOptions({
+        cwd: join(cwd, "fixtures", "targets"),
+        filename: "./node_modules/dep/test.js",
+        babelrcRoots: ["./node_modules/dep/"],
       }).targets,
     ).toEqual({ edge: "14.0.0" });
   });

packages/babel-preset-env/test/regressions.js

@@ -5,17 +5,19 @@ import { fileURLToPath } from "url";
 
 describe("#12880", () => {
   it("read the .browserslistrc file when using @babel/core < 7.13.0", () => {
+    const root = path.join(
+      path.dirname(fileURLToPath(import.meta.url)),
+      "regressions",
+    );
+
     // The browserslistrc file contains "firefox 50".
     // a ** b is supported starting from firefox 52;
     // a => b is supported starting from firefox 45.
     const out = babel7_12.transformSync("a ** b; a => b;", {
       configFile: false,
       presets: [[env, { modules: false }]],
-      filename: path.join(
-        path.dirname(fileURLToPath(import.meta.url)),
-        "regressions",
-        "input.js",
-      ),
+      filename: path.join(root, "input.js"),
+      root,
     });
 
     expect(out.code).toMatchInlineSnapshot(`