diff --git a/packages/babel-core/src/config/build-config-chain.js b/packages/babel-core/src/config/build-config-chain.js
index 5b4b8cee24..ab253cf8dc 100644
--- a/packages/babel-core/src/config/build-config-chain.js
+++ b/packages/babel-core/src/config/build-config-chain.js
@@ -1,6 +1,5 @@
 // @flow
 
-import { getEnv } from "./helpers/environment";
 import path from "path";
 import micromatch from "micromatch";
 import buildDebug from "debug";
@@ -41,20 +40,20 @@ type ConfigPart =
 
 export default function buildConfigChain(
   opts: ValidatedOptions,
+  envName: string,
 ): Array<ConfigItem> | null {
   const filename = opts.filename ? path.resolve(opts.filename) : null;
   const builder = new ConfigChainBuilder(
     filename ? new LoadedFile(filename) : null,
   );
 
-  const envKey = getEnv();
   try {
-    builder.mergeConfigArguments(opts, process.cwd(), envKey);
+    builder.mergeConfigArguments(opts, process.cwd(), envName);
 
     // resolve all .babelrc files
     if (opts.babelrc !== false && filename) {
-      findConfigs(path.dirname(filename)).forEach(configFile =>
-        builder.mergeConfigFile(configFile, envKey),
+      findConfigs(path.dirname(filename), envName).forEach(configFile =>
+        builder.mergeConfigFile(configFile, envName),
       );
     }
   } catch (e) {
@@ -85,21 +84,21 @@ class ConfigChainBuilder {
     );
   }
 
-  mergeConfigFile(file: ConfigFile, envKey: string) {
+  mergeConfigFile(file: ConfigFile, envName: string) {
     if (this.seenFiles.has(file)) {
       throw new Error(
         `Cycle detected in Babel configuration file through "${file.filepath}".`,
       );
     }
 
-    const parts = flattenFileOptionsParts(file)(envKey);
+    const parts = flattenFileOptionsParts(file)(envName);
 
     this.seenFiles.add(file);
-    parts.forEach(part => this._processConfigPart(part, envKey));
+    parts.forEach(part => this._processConfigPart(part, envName));
     this.seenFiles.delete(file);
   }
 
-  _processConfigPart(part: ConfigPart, envKey: string) {
+  _processConfigPart(part: ConfigPart, envName: string) {
     if (part.part === "config") {
       const { ignore, only } = part;
 
@@ -116,7 +115,10 @@ class ConfigChainBuilder {
 
       this.configs.push(part.config);
     } else {
-      this.mergeConfigFile(loadConfig(part.path, part.dirname), envKey);
+      this.mergeConfigFile(
+        loadConfig(part.path, part.dirname, envName),
+        envName,
+      );
     }
   }
 }
@@ -129,7 +131,7 @@ class ConfigChainBuilder {
 function flattenArgumentsOptionsParts(
   opts: ValidatedOptions,
   dirname: string,
-  envKey: string,
+  envName: string,
 ): Array<ConfigPart> {
   const {
     env,
@@ -142,7 +144,7 @@ function flattenArgumentsOptionsParts(
 
   const raw = [];
   if (env) {
-    raw.push(...flattenArgumentsEnvOptionsParts(env)(dirname)(envKey));
+    raw.push(...flattenArgumentsEnvOptionsParts(env)(dirname)(envName));
   }
 
   if (Object.keys(options).length > 0) {
@@ -263,7 +265,7 @@ function flattenOptionsPartsLookup(
     });
   }
 
-  return envKey => lookup.get(envKey) || def;
+  return envName => lookup.get(envName) || def;
 }
 
 /**
diff --git a/packages/babel-core/src/config/loading/files/configuration.js b/packages/babel-core/src/config/loading/files/configuration.js
index 95ec12e98e..a8caa01cdc 100644
--- a/packages/babel-core/src/config/loading/files/configuration.js
+++ b/packages/babel-core/src/config/loading/files/configuration.js
@@ -5,8 +5,7 @@ import path from "path";
 import fs from "fs";
 import json5 from "json5";
 import resolve from "resolve";
-import { getEnv } from "../../helpers/environment";
-import { makeStrongCache } from "../../caching";
+import { makeStrongCache, type CacheConfigurator } from "../../caching";
 
 const debug = buildDebug("babel:config:loading:files:configuration");
 
@@ -21,7 +20,10 @@ const BABELRC_JS_FILENAME = ".babelrc.js";
 const PACKAGE_FILENAME = "package.json";
 const BABELIGNORE_FILENAME = ".babelignore";
 
-export function findConfigs(dirname: string): Array<ConfigFile> {
+export function findConfigs(
+  dirname: string,
+  envName: string,
+): Array<ConfigFile> {
   let foundConfig = false;
   let foundIgnore = false;
 
@@ -47,7 +49,7 @@ export function findConfigs(dirname: string): Array<ConfigFile> {
         PACKAGE_FILENAME,
       ].reduce((previousConfig: ConfigFile | null, name) => {
         const filepath = path.join(loc, name);
-        const config = readConfig(filepath);
+        const config = readConfig(filepath, envName);
 
         if (config && previousConfig) {
           throw new Error(
@@ -77,10 +79,14 @@ export function findConfigs(dirname: string): Array<ConfigFile> {
   return confs;
 }
 
-export function loadConfig(name: string, dirname: string): ConfigFile {
+export function loadConfig(
+  name: string,
+  dirname: string,
+  envName: string,
+): ConfigFile {
   const filepath = resolve.sync(name, { basedir: dirname });
 
-  const conf = readConfig(filepath);
+  const conf = readConfig(filepath, envName);
   if (!conf) {
     throw new Error(`Config file ${filepath} contains no configuration data`);
   }
@@ -93,83 +99,86 @@ export function loadConfig(name: string, dirname: string): ConfigFile {
  * Read the given config file, returning the result. Returns null if no config was found, but will
  * throw if there are parsing errors while loading a config.
  */
-function readConfig(filepath) {
+function readConfig(filepath, envName) {
   return path.extname(filepath) === ".js"
-    ? readConfigJS(filepath)
+    ? readConfigJS(filepath, { envName })
     : readConfigFile(filepath);
 }
 
 const LOADING_CONFIGS = new Set();
-const readConfigJS = makeStrongCache((filepath, cache) => {
-  if (!fs.existsSync(filepath)) {
-    cache.forever();
-    return null;
-  }
 
-  // The `require()` call below can make this code reentrant if a require hook like @babel/register has been
-  // loaded into the system. That would cause Babel to attempt to compile the `.babelrc.js` file as it loads
-  // below. To cover this case, we auto-ignore re-entrant config processing.
-  if (LOADING_CONFIGS.has(filepath)) {
-    cache.never();
+const readConfigJS = makeStrongCache(
+  (filepath, cache: CacheConfigurator<{ envName: string }>) => {
+    if (!fs.existsSync(filepath)) {
+      cache.forever();
+      return null;
+    }
+
+    // The `require()` call below can make this code reentrant if a require hook like @babel/register has been
+    // loaded into the system. That would cause Babel to attempt to compile the `.babelrc.js` file as it loads
+    // below. To cover this case, we auto-ignore re-entrant config processing.
+    if (LOADING_CONFIGS.has(filepath)) {
+      cache.never();
+
+      debug("Auto-ignoring usage of config %o.", filepath);
+      return {
+        filepath,
+        dirname: path.dirname(filepath),
+        options: {},
+      };
+    }
+
+    let options;
+    try {
+      LOADING_CONFIGS.add(filepath);
+
+      // $FlowIssue
+      const configModule = (require(filepath): mixed);
+      options =
+        configModule && configModule.__esModule
+          ? configModule.default || undefined
+          : configModule;
+    } catch (err) {
+      err.message = `${filepath}: Error while loading config - ${err.message}`;
+      throw err;
+    } finally {
+      LOADING_CONFIGS.delete(filepath);
+    }
+
+    if (typeof options === "function") {
+      options = options({
+        cache: cache.simple(),
+        // Expose ".env()" so people can easily get the same env that we expose using the "env" key.
+        env: () => cache.using(data => data.envName),
+        async: () => false,
+      });
+
+      if (!cache.configured()) throwConfigError();
+    }
+
+    if (!options || typeof options !== "object" || Array.isArray(options)) {
+      throw new Error(
+        `${filepath}: Configuration should be an exported JavaScript object.`,
+      );
+    }
+
+    if (typeof options.then === "function") {
+      throw new Error(
+        `You appear to be using an async configuration, ` +
+          `which your current version of Babel does not support. ` +
+          `We may add support for this in the future, ` +
+          `but if you're on the most recent version of @babel/core and still ` +
+          `seeing this error, then you'll need to synchronously return your config.`,
+      );
+    }
 
-    debug("Auto-ignoring usage of config %o.", filepath);
     return {
       filepath,
       dirname: path.dirname(filepath),
-      options: {},
+      options,
     };
-  }
-
-  let options;
-  try {
-    LOADING_CONFIGS.add(filepath);
-
-    // $FlowIssue
-    const configModule = (require(filepath): mixed);
-    options =
-      configModule && configModule.__esModule
-        ? configModule.default || undefined
-        : configModule;
-  } catch (err) {
-    err.message = `${filepath}: Error while loading config - ${err.message}`;
-    throw err;
-  } finally {
-    LOADING_CONFIGS.delete(filepath);
-  }
-
-  if (typeof options === "function") {
-    options = options({
-      cache: cache.simple(),
-      // Expose ".env()" so people can easily get the same env that we expose using the "env" key.
-      env: () => cache.using(() => getEnv()),
-      async: () => false,
-    });
-
-    if (!cache.configured()) throwConfigError();
-  }
-
-  if (!options || typeof options !== "object" || Array.isArray(options)) {
-    throw new Error(
-      `${filepath}: Configuration should be an exported JavaScript object.`,
-    );
-  }
-
-  if (typeof options.then === "function") {
-    throw new Error(
-      `You appear to be using an async configuration, ` +
-        `which your current version of Babel does not support. ` +
-        `We may add support for this in the future, ` +
-        `but if you're on the most recent version of @babel/core and still ` +
-        `seeing this error, then you'll need to synchronously return your config.`,
-    );
-  }
-
-  return {
-    filepath,
-    dirname: path.dirname(filepath),
-    options,
-  };
-});
+  },
+);
 
 const readConfigFile = makeStaticFileCache((filepath, content) => {
   let options;
diff --git a/packages/babel-core/src/config/option-manager.js b/packages/babel-core/src/config/option-manager.js
index 7d7ec5d978..cd7a96a96e 100644
--- a/packages/babel-core/src/config/option-manager.js
+++ b/packages/babel-core/src/config/option-manager.js
@@ -6,7 +6,7 @@ import merge from "lodash/merge";
 import buildConfigChain, { type ConfigItem } from "./build-config-chain";
 import traverse from "@babel/traverse";
 import clone from "lodash/clone";
-import { makeWeakCache } from "./caching";
+import { makeWeakCache, type CacheConfigurator } from "./caching";
 import { getEnv } from "./helpers/environment";
 import { validate, type ValidatedOptions, type PluginItem } from "./options";
 
@@ -46,14 +46,14 @@ class OptionManager {
    *  - `dirname` is used to resolve plugins relative to it.
    */
 
-  mergeOptions(config: MergeOptions, pass?: Array<Plugin>) {
+  mergeOptions(config: MergeOptions, pass?: Array<Plugin>, envName: string) {
     const result = loadConfig(config);
 
     const plugins = result.plugins.map(descriptor =>
-      loadPluginDescriptor(descriptor),
+      loadPluginDescriptor(descriptor, envName),
     );
     const presets = result.presets.map(descriptor =>
-      loadPresetDescriptor(descriptor),
+      loadPresetDescriptor(descriptor, envName),
     );
 
     const passPerPreset = config.options.passPerPreset;
@@ -70,7 +70,11 @@ class OptionManager {
       }
 
       presets.forEach((presetConfig, i) => {
-        this.mergeOptions(presetConfig, presetPasses ? presetPasses[i] : pass);
+        this.mergeOptions(
+          presetConfig,
+          presetPasses ? presetPasses[i] : pass,
+          envName,
+        );
       });
     }
 
@@ -99,12 +103,14 @@ class OptionManager {
   init(inputOpts: {}) {
     const args = validate("arguments", inputOpts);
 
-    const configChain = buildConfigChain(args);
+    const envName = getEnv();
+
+    const configChain = buildConfigChain(args, envName);
     if (!configChain) return null;
 
     try {
       for (const config of configChain) {
-        this.mergeOptions(config);
+        this.mergeOptions(config, undefined, envName);
       }
     } catch (e) {
       // There are a few case where thrown errors will try to annotate themselves multiple times, so
@@ -182,13 +188,13 @@ const loadConfig = makeWeakCache((config: MergeOptions): {
 const loadDescriptor = makeWeakCache(
   (
     { value, options = {}, dirname, alias }: BasicDescriptor,
-    cache,
+    cache: CacheConfigurator<{ envName: string }>,
   ): LoadedDescriptor => {
     let item = value;
     if (typeof value === "function") {
       const api = Object.assign(Object.create(context), {
         cache: cache.simple(),
-        env: () => cache.using(() => getEnv()),
+        env: () => cache.using(data => data.envName),
         async: () => false,
       });
 
@@ -222,7 +228,10 @@ const loadDescriptor = makeWeakCache(
 /**
  * Instantiate a plugin for the given descriptor, returning the plugin/options pair.
  */
-function loadPluginDescriptor(descriptor: BasicDescriptor): Plugin {
+function loadPluginDescriptor(
+  descriptor: BasicDescriptor,
+  envName: string,
+): Plugin {
   if (descriptor.value instanceof Plugin) {
     if (descriptor.options) {
       throw new Error(
@@ -233,11 +242,16 @@ function loadPluginDescriptor(descriptor: BasicDescriptor): Plugin {
     return descriptor.value;
   }
 
-  return instantiatePlugin(loadDescriptor(descriptor));
+  return instantiatePlugin(loadDescriptor(descriptor, { envName }), {
+    envName,
+  });
 }
 
 const instantiatePlugin = makeWeakCache(
-  ({ value, options, dirname, alias }: LoadedDescriptor, cache): Plugin => {
+  (
+    { value, options, dirname, alias }: LoadedDescriptor,
+    cache: CacheConfigurator<{ envName: string }>,
+  ): Plugin => {
     const pluginObj = validatePluginObject(value);
 
     const plugin = Object.assign({}, pluginObj);
@@ -254,8 +268,8 @@ const instantiatePlugin = makeWeakCache(
       };
 
       // If the inherited plugin changes, reinstantiate this plugin.
-      const inherits = cache.invalidate(() =>
-        loadPluginDescriptor(inheritsDescriptor),
+      const inherits = cache.invalidate(data =>
+        loadPluginDescriptor(inheritsDescriptor, data.envName),
       );
 
       plugin.pre = chain(inherits.pre, plugin.pre);
@@ -277,8 +291,11 @@ const instantiatePlugin = makeWeakCache(
 /**
  * Generate a config object that will act as the root of a new nested config.
  */
-const loadPresetDescriptor = (descriptor: BasicDescriptor): MergeOptions => {
-  return instantiatePreset(loadDescriptor(descriptor));
+const loadPresetDescriptor = (
+  descriptor: BasicDescriptor,
+  envName: string,
+): MergeOptions => {
+  return instantiatePreset(loadDescriptor(descriptor, { envName }));
 };
 
 const instantiatePreset = makeWeakCache(
diff --git a/packages/babel-core/test/config-chain.js b/packages/babel-core/test/config-chain.js
index 097112cb07..d4bb482212 100644
--- a/packages/babel-core/test/config-chain.js
+++ b/packages/babel-core/test/config-chain.js
@@ -3,6 +3,8 @@ import fs from "fs";
 import path from "path";
 import buildConfigChain from "../lib/config/build-config-chain";
 
+const DEFAULT_ENV = "development";
+
 function fixture() {
   const args = [__dirname, "fixtures", "config"];
   for (let i = 0; i < arguments.length; i++) {
@@ -16,49 +18,39 @@ function base() {
 }
 
 describe("buildConfigChain", function() {
-  let oldBabelEnv;
-  let oldNodeEnv;
-
-  beforeEach(function() {
-    oldBabelEnv = process.env.BABEL_ENV;
-    oldNodeEnv = process.env.NODE_ENV;
-
-    delete process.env.BABEL_ENV;
-    delete process.env.NODE_ENV;
-  });
-
-  afterEach(function() {
-    process.env.BABEL_ENV = oldBabelEnv;
-    process.env.NODE_ENV = oldNodeEnv;
-  });
-
   describe("ignore", () => {
     it("should ignore files that match", () => {
-      const chain = buildConfigChain({
-        filename: fixture("nonexistant-fake", "src.js"),
-        babelrc: false,
-        ignore: [
-          fixture("nonexistant-fake", "src.js"),
+      const chain = buildConfigChain(
+        {
+          filename: fixture("nonexistant-fake", "src.js"),
+          babelrc: false,
+          ignore: [
+            fixture("nonexistant-fake", "src.js"),
 
-          // We had a regression where multiple ignore patterns broke things, so
-          // we keep some extra random items in here.
-          fixture("nonexistant-fake", "other.js"),
-          fixture("nonexistant-fake", "misc.js"),
-        ],
-      });
+            // We had a regression where multiple ignore patterns broke things, so
+            // we keep some extra random items in here.
+            fixture("nonexistant-fake", "other.js"),
+            fixture("nonexistant-fake", "misc.js"),
+          ],
+        },
+        DEFAULT_ENV,
+      );
 
       assert.equal(chain, null);
     });
 
     it("should not ignore files that don't match", () => {
-      const chain = buildConfigChain({
-        filename: fixture("nonexistant-fake", "src.js"),
-        babelrc: false,
-        ignore: [
-          fixture("nonexistant-fake", "other.js"),
-          fixture("nonexistant-fake", "misc.js"),
-        ],
-      });
+      const chain = buildConfigChain(
+        {
+          filename: fixture("nonexistant-fake", "src.js"),
+          babelrc: false,
+          ignore: [
+            fixture("nonexistant-fake", "other.js"),
+            fixture("nonexistant-fake", "misc.js"),
+          ],
+        },
+        DEFAULT_ENV,
+      );
 
       const expected = [
         {
@@ -82,27 +74,33 @@ describe("buildConfigChain", function() {
 
   describe("only", () => {
     it("should ignore files that don't match", () => {
-      const chain = buildConfigChain({
-        filename: fixture("nonexistant-fake", "src.js"),
-        babelrc: false,
-        only: [
-          fixture("nonexistant-fake", "other.js"),
-          fixture("nonexistant-fake", "misc.js"),
-        ],
-      });
+      const chain = buildConfigChain(
+        {
+          filename: fixture("nonexistant-fake", "src.js"),
+          babelrc: false,
+          only: [
+            fixture("nonexistant-fake", "other.js"),
+            fixture("nonexistant-fake", "misc.js"),
+          ],
+        },
+        DEFAULT_ENV,
+      );
 
       assert.equal(chain, null);
     });
 
     it("should not ignore files that match", () => {
-      const chain = buildConfigChain({
-        filename: fixture("nonexistant-fake", "src.js"),
-        babelrc: false,
-        only: [
-          fixture("nonexistant-fake", "src.js"),
-          fixture("nonexistant-fake", "misc.js"),
-        ],
-      });
+      const chain = buildConfigChain(
+        {
+          filename: fixture("nonexistant-fake", "src.js"),
+          babelrc: false,
+          only: [
+            fixture("nonexistant-fake", "src.js"),
+            fixture("nonexistant-fake", "misc.js"),
+          ],
+        },
+        DEFAULT_ENV,
+      );
 
       const expected = [
         {
@@ -126,12 +124,15 @@ describe("buildConfigChain", function() {
 
   describe("ignore/only", () => {
     it("should ignore files that match ignore and don't match only", () => {
-      const chain = buildConfigChain({
-        filename: fixture("nonexistant-fake", "src.js"),
-        babelrc: false,
-        ignore: [fixture("nonexistant-fake", "src.js")],
-        only: [fixture("nonexistant-fake", "src.js")],
-      });
+      const chain = buildConfigChain(
+        {
+          filename: fixture("nonexistant-fake", "src.js"),
+          babelrc: false,
+          ignore: [fixture("nonexistant-fake", "src.js")],
+          only: [fixture("nonexistant-fake", "src.js")],
+        },
+        DEFAULT_ENV,
+      );
 
       assert.equal(chain, null);
     });
@@ -142,8 +143,8 @@ describe("buildConfigChain", function() {
       it("should not cache the input options by identity", () => {
         const comments = false;
 
-        const chain1 = buildConfigChain({ comments });
-        const chain2 = buildConfigChain({ comments });
+        const chain1 = buildConfigChain({ comments }, DEFAULT_ENV);
+        const chain2 = buildConfigChain({ comments }, DEFAULT_ENV);
 
         assert.equal(chain1.length, 1);
         assert.equal(chain2.length, 1);
@@ -151,15 +152,14 @@ describe("buildConfigChain", function() {
       });
 
       it("should cache the env options by identity", () => {
-        process.env.NODE_ENV = "foo";
         const env = {
           foo: {
             comments: false,
           },
         };
 
-        const chain1 = buildConfigChain({ env });
-        const chain2 = buildConfigChain({ env });
+        const chain1 = buildConfigChain({ env }, "foo");
+        const chain2 = buildConfigChain({ env }, "foo");
 
         assert.equal(chain1.length, 2);
         assert.equal(chain2.length, 2);
@@ -170,8 +170,8 @@ describe("buildConfigChain", function() {
       it("should cache the plugin options by identity", () => {
         const plugins = [];
 
-        const chain1 = buildConfigChain({ plugins });
-        const chain2 = buildConfigChain({ plugins });
+        const chain1 = buildConfigChain({ plugins }, DEFAULT_ENV);
+        const chain2 = buildConfigChain({ plugins }, DEFAULT_ENV);
 
         assert.equal(chain1.length, 1);
         assert.equal(chain2.length, 1);
@@ -181,8 +181,8 @@ describe("buildConfigChain", function() {
       it("should cache the presets options by identity", () => {
         const presets = [];
 
-        const chain1 = buildConfigChain({ presets });
-        const chain2 = buildConfigChain({ presets });
+        const chain1 = buildConfigChain({ presets }, DEFAULT_ENV);
+        const chain2 = buildConfigChain({ presets }, DEFAULT_ENV);
 
         assert.equal(chain1.length, 1);
         assert.equal(chain2.length, 1);
@@ -192,9 +192,15 @@ describe("buildConfigChain", function() {
       it("should not cache the presets options with passPerPreset", () => {
         const presets = [];
 
-        const chain1 = buildConfigChain({ presets });
-        const chain2 = buildConfigChain({ presets, passPerPreset: true });
-        const chain3 = buildConfigChain({ presets, passPerPreset: false });
+        const chain1 = buildConfigChain({ presets }, DEFAULT_ENV);
+        const chain2 = buildConfigChain(
+          { presets, passPerPreset: true },
+          DEFAULT_ENV,
+        );
+        const chain3 = buildConfigChain(
+          { presets, passPerPreset: false },
+          DEFAULT_ENV,
+        );
 
         assert.equal(chain1.length, 1);
         assert.equal(chain2.length, 1);
@@ -229,13 +235,13 @@ describe("buildConfigChain", function() {
           "package.json",
         );
 
-        const chain1 = buildConfigChain({ filename });
-        const chain2 = buildConfigChain({ filename });
+        const chain1 = buildConfigChain({ filename }, DEFAULT_ENV);
+        const chain2 = buildConfigChain({ filename }, DEFAULT_ENV);
 
         touch(pkgJSON);
 
-        const chain3 = buildConfigChain({ filename });
-        const chain4 = buildConfigChain({ filename });
+        const chain3 = buildConfigChain({ filename }, DEFAULT_ENV);
+        const chain4 = buildConfigChain({ filename }, DEFAULT_ENV);
 
         assert.equal(chain1.length, 3);
         assert.equal(chain2.length, 3);
@@ -266,13 +272,13 @@ describe("buildConfigChain", function() {
           ".babelrc",
         );
 
-        const chain1 = buildConfigChain({ filename });
-        const chain2 = buildConfigChain({ filename });
+        const chain1 = buildConfigChain({ filename }, DEFAULT_ENV);
+        const chain2 = buildConfigChain({ filename }, DEFAULT_ENV);
 
         touch(babelrcFile);
 
-        const chain3 = buildConfigChain({ filename });
-        const chain4 = buildConfigChain({ filename });
+        const chain3 = buildConfigChain({ filename }, DEFAULT_ENV);
+        const chain4 = buildConfigChain({ filename }, DEFAULT_ENV);
 
         assert.equal(chain1.length, 3);
         assert.equal(chain2.length, 3);
@@ -303,13 +309,13 @@ describe("buildConfigChain", function() {
           ".babelignore",
         );
 
-        const chain1 = buildConfigChain({ filename });
-        const chain2 = buildConfigChain({ filename });
+        const chain1 = buildConfigChain({ filename }, DEFAULT_ENV);
+        const chain2 = buildConfigChain({ filename }, DEFAULT_ENV);
 
         touch(babelignoreFile);
 
-        const chain3 = buildConfigChain({ filename });
-        const chain4 = buildConfigChain({ filename });
+        const chain3 = buildConfigChain({ filename }, DEFAULT_ENV);
+        const chain4 = buildConfigChain({ filename }, DEFAULT_ENV);
 
         assert.equal(chain1.length, 6);
         assert.equal(chain2.length, 6);
@@ -340,13 +346,11 @@ describe("buildConfigChain", function() {
           ".babelrc.js",
         );
 
-        const chain1 = buildConfigChain({ filename });
-        const chain2 = buildConfigChain({ filename });
+        const chain1 = buildConfigChain({ filename }, DEFAULT_ENV);
+        const chain2 = buildConfigChain({ filename }, DEFAULT_ENV);
 
-        process.env.NODE_ENV = "new-env";
-
-        const chain3 = buildConfigChain({ filename });
-        const chain4 = buildConfigChain({ filename });
+        const chain3 = buildConfigChain({ filename }, "new-env");
+        const chain4 = buildConfigChain({ filename }, "new-env");
 
         assert.equal(chain1.length, 3);
         assert.equal(chain2.length, 3);
@@ -358,7 +362,7 @@ describe("buildConfigChain", function() {
         assert.equal(chain4[1].alias, babelrcFile);
         assert.strictEqual(chain1[1], chain2[1]);
 
-        // Identity changed after changing the NODE_ENV.
+        // Identity changed after changing the envName.
         assert.notStrictEqual(chain3[1], chain1[1]);
         assert.strictEqual(chain3[1], chain4[1]);
       });
@@ -366,9 +370,12 @@ describe("buildConfigChain", function() {
   });
 
   it("dir1", function() {
-    const chain = buildConfigChain({
-      filename: fixture("dir1", "src.js"),
-    });
+    const chain = buildConfigChain(
+      {
+        filename: fixture("dir1", "src.js"),
+      },
+      DEFAULT_ENV,
+    );
 
     const expected = [
       {
@@ -410,9 +417,12 @@ describe("buildConfigChain", function() {
   });
 
   it("dir2", function() {
-    const chain = buildConfigChain({
-      filename: fixture("dir2", "src.js"),
-    });
+    const chain = buildConfigChain(
+      {
+        filename: fixture("dir2", "src.js"),
+      },
+      DEFAULT_ENV,
+    );
 
     const expected = [
       {
@@ -445,9 +455,12 @@ describe("buildConfigChain", function() {
   });
 
   it("dir3", function() {
-    const chain = buildConfigChain({
-      filename: fixture("dir3", "src.js"),
-    });
+    const chain = buildConfigChain(
+      {
+        filename: fixture("dir3", "src.js"),
+      },
+      DEFAULT_ENV,
+    );
 
     const expected = [
       {
@@ -489,9 +502,12 @@ describe("buildConfigChain", function() {
   });
 
   it("env - base", function() {
-    const chain = buildConfigChain({
-      filename: fixture("env", "src.js"),
-    });
+    const chain = buildConfigChain(
+      {
+        filename: fixture("env", "src.js"),
+      },
+      DEFAULT_ENV,
+    );
 
     const expected = [
       {
@@ -532,11 +548,12 @@ describe("buildConfigChain", function() {
   });
 
   it("env - foo", function() {
-    process.env.NODE_ENV = "foo";
-
-    const chain = buildConfigChain({
-      filename: fixture("env", "src.js"),
-    });
+    const chain = buildConfigChain(
+      {
+        filename: fixture("env", "src.js"),
+      },
+      "foo",
+    );
 
     const expected = [
       {
@@ -585,12 +602,12 @@ describe("buildConfigChain", function() {
   });
 
   it("env - bar", function() {
-    process.env.NODE_ENV = "foo"; // overridden
-    process.env.NODE_ENV = "bar";
-
-    const chain = buildConfigChain({
-      filename: fixture("env", "src.js"),
-    });
+    const chain = buildConfigChain(
+      {
+        filename: fixture("env", "src.js"),
+      },
+      "bar",
+    );
 
     const expected = [
       {
@@ -639,11 +656,12 @@ describe("buildConfigChain", function() {
   });
 
   it("env - foo", function() {
-    process.env.NODE_ENV = "foo";
-
-    const chain = buildConfigChain({
-      filename: fixture("pkg", "src.js"),
-    });
+    const chain = buildConfigChain(
+      {
+        filename: fixture("pkg", "src.js"),
+      },
+      "foo",
+    );
 
     const expected = [
       {
@@ -676,9 +694,12 @@ describe("buildConfigChain", function() {
   });
 
   it("js-config", function() {
-    const chain = buildConfigChain({
-      filename: fixture("js-config", "src.js"),
-    });
+    const chain = buildConfigChain(
+      {
+        filename: fixture("js-config", "src.js"),
+      },
+      DEFAULT_ENV,
+    );
 
     const expected = [
       {
@@ -711,9 +732,12 @@ describe("buildConfigChain", function() {
   });
 
   it("js-config-function", function() {
-    const chain = buildConfigChain({
-      filename: fixture("js-config-function", "src.js"),
-    });
+    const chain = buildConfigChain(
+      {
+        filename: fixture("js-config-function", "src.js"),
+      },
+      DEFAULT_ENV,
+    );
 
     const expected = [
       {
@@ -746,9 +770,12 @@ describe("buildConfigChain", function() {
   });
 
   it("js-config-default - should read transpiled export default", function() {
-    const chain = buildConfigChain({
-      filename: fixture("js-config-default", "src.js"),
-    });
+    const chain = buildConfigChain(
+      {
+        filename: fixture("js-config-default", "src.js"),
+      },
+      DEFAULT_ENV,
+    );
 
     const expected = [
       {
@@ -780,9 +807,12 @@ describe("buildConfigChain", function() {
     assert.deepEqual(chain, expected);
   });
   it("js-config-extended", function() {
-    const chain = buildConfigChain({
-      filename: fixture("js-config-extended", "src.js"),
-    });
+    const chain = buildConfigChain(
+      {
+        filename: fixture("js-config-extended", "src.js"),
+      },
+      DEFAULT_ENV,
+    );
 
     const expected = [
       {
@@ -827,9 +857,12 @@ describe("buildConfigChain", function() {
     "json-pkg-config-no-babel - should not throw if" +
       " package.json doesn't contain a `babel` field",
     function() {
-      const chain = buildConfigChain({
-        filename: fixture("json-pkg-config-no-babel", "src.js"),
-      });
+      const chain = buildConfigChain(
+        {
+          filename: fixture("json-pkg-config-no-babel", "src.js"),
+        },
+        DEFAULT_ENV,
+      );
 
       const expected = [
         {
@@ -863,9 +896,12 @@ describe("buildConfigChain", function() {
   );
 
   it("should not ignore file matching negated file pattern", function() {
-    const chain = buildConfigChain({
-      filename: fixture("ignore-negate", "src.js"),
-    });
+    const chain = buildConfigChain(
+      {
+        filename: fixture("ignore-negate", "src.js"),
+      },
+      DEFAULT_ENV,
+    );
 
     const expected = [
       {
@@ -896,17 +932,23 @@ describe("buildConfigChain", function() {
 
     assert.deepEqual(chain, expected);
 
-    const chain2 = buildConfigChain({
-      filename: fixture("ignore-negate", "src2.js"),
-    });
+    const chain2 = buildConfigChain(
+      {
+        filename: fixture("ignore-negate", "src2.js"),
+      },
+      DEFAULT_ENV,
+    );
 
     assert.equal(chain2, null);
   });
 
   it("should not ignore file matching negated folder pattern", function() {
-    const chain = buildConfigChain({
-      filename: fixture("ignore-negate-folder", "folder", "src.js"),
-    });
+    const chain = buildConfigChain(
+      {
+        filename: fixture("ignore-negate-folder", "folder", "src.js"),
+      },
+      DEFAULT_ENV,
+    );
 
     const expected = [
       {
@@ -937,9 +979,12 @@ describe("buildConfigChain", function() {
 
     assert.deepEqual(chain, expected);
 
-    const chain2 = buildConfigChain({
-      filename: fixture("ignore-negate-folder", "src2.js"),
-    });
+    const chain2 = buildConfigChain(
+      {
+        filename: fixture("ignore-negate-folder", "src2.js"),
+      },
+      DEFAULT_ENV,
+    );
 
     assert.equal(chain2, null);
   });
@@ -949,9 +994,12 @@ describe("buildConfigChain", function() {
       " and a .babelrc.js are present",
     function() {
       assert.throws(function() {
-        buildConfigChain({
-          filename: fixture("js-json-config", "src.js"),
-        });
+        buildConfigChain(
+          {
+            filename: fixture("js-json-config", "src.js"),
+          },
+          DEFAULT_ENV,
+        );
       }, /Multiple configuration files found\.(.|\n)*\.babelrc(.|\n)*\.babelrc\.js/);
     },
   );
@@ -961,9 +1009,12 @@ describe("buildConfigChain", function() {
       " and a package.json with a babel field are present",
     function() {
       assert.throws(function() {
-        buildConfigChain({
-          filename: fixture("js-pkg-config", "src.js"),
-        });
+        buildConfigChain(
+          {
+            filename: fixture("js-pkg-config", "src.js"),
+          },
+          DEFAULT_ENV,
+        );
       }, /Multiple configuration files found\.(.|\n)*\.babelrc\.js(.|\n)*package\.json/);
     },
   );
@@ -973,42 +1024,57 @@ describe("buildConfigChain", function() {
       " and a package.json with a babel field are present",
     function() {
       assert.throws(function() {
-        buildConfigChain({
-          filename: fixture("json-pkg-config", "src.js"),
-        });
+        buildConfigChain(
+          {
+            filename: fixture("json-pkg-config", "src.js"),
+          },
+          DEFAULT_ENV,
+        );
       }, /Multiple configuration files found\.(.|\n)*\.babelrc(.|\n)*package\.json/);
     },
   );
 
   it("js-config-error", function() {
     assert.throws(function() {
-      buildConfigChain({
-        filename: fixture("js-config-error", "src.js"),
-      });
+      buildConfigChain(
+        {
+          filename: fixture("js-config-error", "src.js"),
+        },
+        DEFAULT_ENV,
+      );
     }, /Error while loading config/);
   });
 
   it("js-config-error2", function() {
     assert.throws(function() {
-      buildConfigChain({
-        filename: fixture("js-config-error2", "src.js"),
-      });
+      buildConfigChain(
+        {
+          filename: fixture("js-config-error2", "src.js"),
+        },
+        DEFAULT_ENV,
+      );
     }, /Configuration should be an exported JavaScript object/);
   });
 
   it("js-config-error3", function() {
     assert.throws(function() {
-      buildConfigChain({
-        filename: fixture("js-config-error3", "src.js"),
-      });
+      buildConfigChain(
+        {
+          filename: fixture("js-config-error3", "src.js"),
+        },
+        DEFAULT_ENV,
+      );
     }, /Configuration should be an exported JavaScript object/);
   });
 
   it("json-config-error", function() {
     assert.throws(function() {
-      buildConfigChain({
-        filename: fixture("json-config-error", "src.js"),
-      });
+      buildConfigChain(
+        {
+          filename: fixture("json-config-error", "src.js"),
+        },
+        DEFAULT_ENV,
+      );
     }, /Error while parsing config/);
   });
 });