style(src): modernize code

src/config.js

@@ -0,0 +1,26 @@
+const path = require("path");
+const exists = require("./utils/exists");
+
+const configs = [".babelrc", ".babelrc.js", "package.json"];
+
+module.exports = function find(fs, start) {
+  for (let config of configs) {
+    config = path.join(start, config);
+
+    if (exists(fs, config)) {
+      if (
+        path.basename(config) !== "package.json" ||
+        typeof require(config).babel === "object"
+      ) {
+        return config;
+      }
+    }
+  }
+
+  const up = path.dirname(start);
+
+  // Reached root
+  if (up !== start) {
+    return find(fs, up);
+  }
+};

src/utils/exists.js

@@ -1,8 +1,8 @@
-module.exports = function(fileSystem, filename) {
+module.exports = function(fs, config) {
   let exists = false;
 
   try {
-    exists = fileSystem.statSync(filename).isFile();
+    exists = fs.statSync(config).isFile();
   } catch (err) {
     if (err.code !== "ENOENT") throw err;
   }

src/utils/read.js

@@ -1,12 +1,12 @@
 const path = require("path");
 
-module.exports = function readBabelConfig(fileSystem, filename) {
-  if (path.basename(filename) === "package.json") {
-    const pkg = require(filename);
+module.exports = function(fs, config) {
+  if (path.basename(config) === "package.json") {
+    const pkg = require(config);
 
     return JSON.stringify(pkg.babel);
   }
 
-  // Webpack `fs` return Buffer
-  return fileSystem.readFileSync(filename).toString("utf8");
+  // memoryFS (webpack) returns a {Buffer}
+  return fs.readFileSync(config).toString("utf-8");
 };

src/utils/relative.js

@@ -1,13 +1,14 @@
 const path = require("path");
 
-module.exports = function relative(sourceRoot, filename) {
-  const rootPath = sourceRoot.replace(/\\/g, "/").split("/")[1];
-  const fileRootPath = filename.replace(/\\/g, "/").split("/")[1];
+module.exports = function relative(root, file) {
+  const rootPath = root.replace(/\\/g, "/").split("/")[1];
+  const filePath = file.replace(/\\/g, "/").split("/")[1];
 
-  // If the file is in a completely different root folder use the absolute path of file.
-  if (rootPath && rootPath !== fileRootPath) {
-    return filename;
+  // If the file is in a completely different root folder
+  // use the absolute path of the file
+  if (rootPath && rootPath !== filePath) {
+    return file;
   }
 
-  return path.relative(sourceRoot, filename);
+  return path.relative(root, file);
 };

test/resolverc.test.js → test/config.test.js

@@ -1,25 +1,27 @@
 import test from "ava";
-import path from "path";
-import resolveRc from "../lib/resolve-rc";
+
 import fs from "fs";
+import path from "path";
+
+import rc from "../lib/config";
 
 test("should find the .babelrc file", t => {
   const start = path.join(__dirname, "fixtures/babelrc-test/1/2/3");
-  const result = resolveRc(fs, start);
+  const result = rc(fs, start);
 
   t.is(result, path.join(__dirname, "fixtures/babelrc-test/.babelrc"));
 });
 
 test("should find the .babelrc.js config", t => {
   const start = path.join(__dirname, "fixtures/babelrc-test/1/2/5/4");
-  const result = resolveRc(fs, start);
+  const result = rc(fs, start);
 
   t.is(result, path.join(__dirname, "fixtures/babelrc-test/1/2/5/.babelrc.js"));
 });
 
 test("should find the package.json babel config", t => {
   const start = path.join(__dirname, "fixtures/package-test");
-  const result = resolveRc(fs, start);
+  const result = rc(fs, start);
 
   t.is(result, path.join(__dirname, "fixtures/package-test/package.json"));
 });