Only base cache identifier on babel options from pkg.json (#468)

.eslintrc

@@ -7,6 +7,7 @@
   "plugins": ["prettier"],
   "rules": {
     "arrow-parens": "off",
+    "quotes": "off",
     "prettier/prettier": ["error", { "trailingComma": "all" }]
   }
 }

src/utils/exists.js

@@ -1,13 +1,9 @@
 module.exports = function(fileSystem, filename) {
-  if (!filename) return false;
-
   let exists = false;
 
   try {
     exists = fileSystem.statSync(filename).isFile();
-  } catch (ignoreError) {
-    return false;
-  }
+  } catch (e) {}
 
   return exists;
 };

src/utils/read.js

@@ -1,6 +1,10 @@
-module.exports = function(fileSystem, filename) {
-  if (!filename) {
-    throw new Error("filename must be a string");
+const path = require("path");
+
+module.exports = function readBabelConfig(fileSystem, filename) {
+  if (path.basename(filename) === "package.json") {
+    const pkg = require(filename);
+
+    return JSON.stringify(pkg.babel);
   }
 
   // Webpack `fs` return Buffer

test/utils/read.test.js

@@ -5,6 +5,7 @@ import read from "../../lib/utils/read.js";
 
 const files = {
   existent: path.join(__dirname, "../fixtures/basic.js"),
+  pkg: path.join(__dirname, "../fixtures/package-test/package.json"),
 };
 
 const content = fs.readFileSync(files.existent, "utf8");
@@ -13,3 +14,8 @@ test("should return contents if file exists", t => {
   const realFile = read(fs, files.existent);
   t.is(realFile, content);
 });
+
+test("should only return config from package.json", t => {
+  const realFile = read(fs, files.pkg);
+  t.is(realFile, '{"stage":3}');
+});