Add test for file-relative addon resolution

Plugins & presets.

packages/babel-core/test/fixtures/resolution/resolve-addons-relative-to-file/.gitignore

@@ -0,0 +1 @@
+!node_modules/

packages/babel-core/test/fixtures/resolution/resolve-addons-relative-to-file/actual.js

@@ -0,0 +1 @@
+var x = "before";

packages/babel-core/test/fixtures/resolution/resolve-addons-relative-to-file/expected.js

@@ -0,0 +1 @@
+var x = "AFTER";

packages/babel-core/test/fixtures/resolution/resolve-addons-relative-to-file/node_modules/addons/plugin.js

@@ -0,0 +1,9 @@
+module.exports = function () {
+  return {
+    visitor: {
+      StringLiteral: function (path) {
+        path.node.value = "after";
+      },
+    },
+  };
+};

packages/babel-core/test/fixtures/resolution/resolve-addons-relative-to-file/node_modules/addons/preset.js

@@ -0,0 +1,14 @@
+module.exports = {
+  plugins: [plugin],
+};
+
+function plugin () {
+  return {
+    visitor: {
+      StringLiteral: function (path) {
+        path.node.value =
+          path.node.value.toUpperCase();
+      },
+    },
+  };
+}

packages/babel-core/test/resolution.js

@@ -0,0 +1,47 @@
+var assert = require("assert");
+var async = require("async");
+var babel = require("../lib/api/node");
+var fs = require("fs");
+var path = require("path");
+
+// Test that plugins & presets are resolved relative to `filename`.
+suite("addon resolution", function () {
+  test("addon resolution", function (done) {
+    var fixtures = {};
+    var paths = {};
+
+    paths.fixtures = path.join(
+      __dirname,
+      "fixtures",
+      "resolution",
+      "resolve-addons-relative-to-file"
+    );
+
+    async.each(
+      ["actual", "expected"],
+      function (key, mapDone) {
+        paths[key] = path.join(paths.fixtures, key + ".js");
+        fs.readFile(paths[key], { encoding: "utf8" }, function (err, data) {
+          if (err) return mapDone(err);
+          fixtures[key] = data.trim();
+          mapDone();
+        });
+      },
+      fixturesReady
+    );
+
+    function fixturesReady (err) {
+      if (err) return done(err);
+
+      var actual = babel.transform(fixtures.actual, {
+        filename: paths.actual,
+        plugins: ["addons/plugin"],
+        presets: ["addons/preset"],
+      }).code;
+
+      assert.equal(actual, fixtures.expected);
+      done();
+    }
+    // fixturesReady
+  });
+});