From ad7f11411cdca825e2e9093554b0fa9fda85783d Mon Sep 17 00:00:00 2001
From: Jared McDonald <jared.r.mcdonald@gmail.com>
Date: Sat, 8 Oct 2016 12:54:44 -0400
Subject: [PATCH 01/12] set up modifyBabelConfig in base config and add it to
 buildConfigs for webpack

---
 utils/buildConfigs.js | 18 +++++++++++++++++-
 utils/kytConfig.js    |  2 +-
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/utils/buildConfigs.js b/utils/buildConfigs.js
index 49d7d918a..d229149dd 100644
--- a/utils/buildConfigs.js
+++ b/utils/buildConfigs.js
@@ -47,7 +47,7 @@ module.exports = (config, environment = 'development') => {
   clientConfig = merge.smart(baseConfig(clientOptions), clientConfig(clientOptions));
   serverConfig = merge.smart(baseConfig(serverOptions), serverConfig(serverOptions));
 
-  // Modify via userland config
+  // Modify via userland webpack config
   try {
     clientConfig = config.modifyWebpackConfig(clone(clientConfig), clientOptions);
     serverConfig = config.modifyWebpackConfig(clone(serverConfig), serverOptions);
@@ -56,6 +56,22 @@ module.exports = (config, environment = 'development') => {
     process.exit(1);
   }
 
+  // Merge in userland babel config via `config.transformBabelConfig`
+  try {
+    [
+      { webpackConfig: clientConfig, options: clientOptions },
+      { webpackConfig: serverConfig, options: serverOptions },
+    ].forEach(({ webpackConfig, options }) => {
+      const babelLoader = webpackConfig.module.loaders.find(({ loader }) => loader === 'babel-loader');
+      Object.assign(babelLoader, {
+        query: config.modifyBabelConfig(clone(babelLoader.query), options),
+      });
+    });
+  } catch (error) {
+    logger.error('Error in your kyt.config.js modifyBabelConfig():', error);
+    process.exit(1);
+  }
+
   if (config.debug) {
     logger.debug('Client webpack configuration:', clientConfig);
     logger.debug('\n\n');
diff --git a/utils/kytConfig.js b/utils/kytConfig.js
index 13633061e..9a0ebd940 100644
--- a/utils/kytConfig.js
+++ b/utils/kytConfig.js
@@ -40,7 +40,7 @@ module.exports = (optionalConfig) => {
   config = mergeAll([{}, baseConfig, config]);
 
   // Create default identity functions for modify functions
-  ['modifyWebpackConfig', 'modifyJestConfig'].forEach((m) => {
+  ['modifyWebpackConfig', 'modifyJestConfig', 'modifyBabelConfig'].forEach((m) => {
     if (typeof config[m] !== 'function') {
       config[m] = c => c;
     }

From 931af3b7da166da75e62af92b65adb9c2c3ab639 Mon Sep 17 00:00:00 2001
From: Jared McDonald <jared.r.mcdonald@gmail.com>
Date: Sat, 8 Oct 2016 13:00:54 -0400
Subject: [PATCH 02/12] use modifyBabelConfig in jest preprocessor

---
 utils/jest/preprocessor.js | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/utils/jest/preprocessor.js b/utils/jest/preprocessor.js
index bb2a4b9a8..7f33f6fb6 100644
--- a/utils/jest/preprocessor.js
+++ b/utils/jest/preprocessor.js
@@ -1,17 +1,7 @@
-const mergeAll = require('ramda').mergeAll;
 const babel = require('../../config/babel')();
 const babelJest = require('babel-jest');
-const buildConfigs = require('../buildConfigs');
 const config = require('../kytConfig')();
 
-const { clientConfig } = buildConfigs(config);
-
-// Merge userland babel config with our babel config
-// This should go away after https://github.com/NYTimes/kyt/issues/134
-const clientBabelConfig = clientConfig.module.loaders
-  .find(loader => loader.loader === 'babel-loader')
-  .query;
-
-const babelConfigForJest = mergeAll([{}, babel, clientBabelConfig]);
+const babelConfigForJest = config.modifyBabelConfig(babel);
 
 module.exports = babelJest.createTransformer(babelConfigForJest);

From 350c1a00ae60b649b2ccbfe04b620de2e6423af1 Mon Sep 17 00:00:00 2001
From: Jared McDonald <jared.r.mcdonald@gmail.com>
Date: Sat, 8 Oct 2016 13:47:15 -0400
Subject: [PATCH 03/12] move call to modifyBabelConfig to config/babel instead
 of tying it to webpack config assembly; get tests to pass

---
 config/__tests__/babel.test.js |  2 ++
 config/babel.js                | 11 ++++++++++-
 utils/__mocks__/kytConfig.js   |  4 ++++
 utils/buildConfigs.js          | 16 ----------------
 utils/jest/preprocessor.js     |  7 ++++++-
 5 files changed, 22 insertions(+), 18 deletions(-)
 create mode 100644 utils/__mocks__/kytConfig.js

diff --git a/config/__tests__/babel.test.js b/config/__tests__/babel.test.js
index 774f5bae2..5113c98d7 100644
--- a/config/__tests__/babel.test.js
+++ b/config/__tests__/babel.test.js
@@ -15,6 +15,8 @@ jest.setMock('path', {
   resolve: a => a,
 });
 
+jest.mock('../../utils/kytConfig');
+
 const babel = require('../babel');
 
 describe('babel', () => {
diff --git a/config/babel.js b/config/babel.js
index 037959d5e..6ebb8adc1 100644
--- a/config/babel.js
+++ b/config/babel.js
@@ -1,5 +1,7 @@
 const path = require('path');
 const fs = require('fs');
+const config = require('../utils/kytConfig')();
+const logger = require('../cli/logger');
 
 // Uses require.resolve to add the full paths to all of the plugins
 // and presets, making sure that we handle the new array syntax.
@@ -26,5 +28,12 @@ module.exports = (options) => {
   }
   Object.keys(babelrc.env || {}).forEach(env => resolvePluginsPresets(babelrc.env[env]));
 
-  return babelrc;
+  // modify via userland kytConfig's `modifyBabelConfig`
+  try {
+    return config.modifyBabelConfig(babelrc, options);
+  } catch (error) {
+    logger.error('Error in your kyt.config.js modifyBabelConfig():', error);
+    // return to satisfy eslint `consistent-return` rule
+    return process.exit(1);
+  }
 };
diff --git a/utils/__mocks__/kytConfig.js b/utils/__mocks__/kytConfig.js
new file mode 100644
index 000000000..b820d7177
--- /dev/null
+++ b/utils/__mocks__/kytConfig.js
@@ -0,0 +1,4 @@
+module.exports = () => ({
+  // TODO add more to this mock (this is all we need for now)
+  modifyBabelConfig: jest.fn(c => c),
+});
diff --git a/utils/buildConfigs.js b/utils/buildConfigs.js
index d229149dd..fdf958b97 100644
--- a/utils/buildConfigs.js
+++ b/utils/buildConfigs.js
@@ -56,22 +56,6 @@ module.exports = (config, environment = 'development') => {
     process.exit(1);
   }
 
-  // Merge in userland babel config via `config.transformBabelConfig`
-  try {
-    [
-      { webpackConfig: clientConfig, options: clientOptions },
-      { webpackConfig: serverConfig, options: serverOptions },
-    ].forEach(({ webpackConfig, options }) => {
-      const babelLoader = webpackConfig.module.loaders.find(({ loader }) => loader === 'babel-loader');
-      Object.assign(babelLoader, {
-        query: config.modifyBabelConfig(clone(babelLoader.query), options),
-      });
-    });
-  } catch (error) {
-    logger.error('Error in your kyt.config.js modifyBabelConfig():', error);
-    process.exit(1);
-  }
-
   if (config.debug) {
     logger.debug('Client webpack configuration:', clientConfig);
     logger.debug('\n\n');
diff --git a/utils/jest/preprocessor.js b/utils/jest/preprocessor.js
index 7f33f6fb6..700e09f99 100644
--- a/utils/jest/preprocessor.js
+++ b/utils/jest/preprocessor.js
@@ -2,6 +2,11 @@ const babel = require('../../config/babel')();
 const babelJest = require('babel-jest');
 const config = require('../kytConfig')();
 
-const babelConfigForJest = config.modifyBabelConfig(babel);
+const options = {
+  type: 'test',
+  environment: 'test',
+};
+
+const babelConfigForJest = config.modifyBabelConfig(babel, options);
 
 module.exports = babelJest.createTransformer(babelConfigForJest);

From 00ffded1289b20083dfd9f44adb01676d334bc36 Mon Sep 17 00:00:00 2001
From: Jared McDonald <jared.r.mcdonald@gmail.com>
Date: Sat, 8 Oct 2016 14:10:29 -0400
Subject: [PATCH 04/12] add basic test for config/babel

---
 config/__tests__/babel.test.js | 19 +++++++++++++++++++
 utils/__mocks__/kytConfig.js   |  4 +++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/config/__tests__/babel.test.js b/config/__tests__/babel.test.js
index 5113c98d7..518fd5200 100644
--- a/config/__tests__/babel.test.js
+++ b/config/__tests__/babel.test.js
@@ -16,10 +16,15 @@ jest.setMock('path', {
 });
 
 jest.mock('../../utils/kytConfig');
+const kytConfig = require('../../utils/kytConfig');
 
 const babel = require('../babel');
 
 describe('babel', () => {
+  beforeEach(() => {
+    kytConfig().modifyBabelConfig.mockClear();
+  });
+
   it('sets flags', () => {
     const babelrc = babel();
     expect(babelrc.babelrc).toBe(false);
@@ -37,4 +42,18 @@ describe('babel', () => {
     expect(babelrc.env.development.plugins).toEqual([thisResolved]);
     expect(babelrc.env.development.presets).toEqual([[thisResolved]]);
   });
+
+  it('calls kytConfig\'s modifyBabelConfig', () => {
+    const opts = {};
+    babel(opts);
+    const config = kytConfig();
+    expect(config.modifyBabelConfig).toBeCalled();
+    expect(config.modifyBabelConfig.mock.calls[0][0]).toEqual(Object.assign({}, stubBabelrc, {
+      babelrc: false,
+      cacheDirectory: false,
+      plugins: [],
+      presets: [],
+    }));
+    expect(config.modifyBabelConfig.mock.calls[0][1]).toBe(opts);
+  });
 });
diff --git a/utils/__mocks__/kytConfig.js b/utils/__mocks__/kytConfig.js
index b820d7177..cb4dd8d00 100644
--- a/utils/__mocks__/kytConfig.js
+++ b/utils/__mocks__/kytConfig.js
@@ -1,4 +1,6 @@
+const modifyBabelConfig = jest.fn(c => c);
+
 module.exports = () => ({
   // TODO add more to this mock (this is all we need for now)
-  modifyBabelConfig: jest.fn(c => c),
+  modifyBabelConfig,
 });

From db9dce11f681ebfab67646d855adaaf80e56da1b Mon Sep 17 00:00:00 2001
From: Jared McDonald <jared.r.mcdonald@gmail.com>
Date: Sat, 8 Oct 2016 15:17:55 -0400
Subject: [PATCH 05/12] test error path for config/babel

---
 config/__tests__/babel.test.js | 27 ++++++++++++++++++++++++---
 utils/__mocks__/kytConfig.js   |  6 ------
 2 files changed, 24 insertions(+), 9 deletions(-)
 delete mode 100644 utils/__mocks__/kytConfig.js

diff --git a/config/__tests__/babel.test.js b/config/__tests__/babel.test.js
index 518fd5200..970584851 100644
--- a/config/__tests__/babel.test.js
+++ b/config/__tests__/babel.test.js
@@ -8,6 +8,7 @@ const stubBabelrc = {
     },
   },
 };
+jest.mock('../../cli/logger');
 jest.setMock('fs', {
   readFileSync: () => JSON.stringify(stubBabelrc),
 });
@@ -15,14 +16,25 @@ jest.setMock('path', {
   resolve: a => a,
 });
 
-jest.mock('../../utils/kytConfig');
-const kytConfig = require('../../utils/kytConfig');
+const modifyBabelConfig = jest.fn(c => c);
+const mockKytConfig = () => ({ modifyBabelConfig });
+jest.setMock('../../utils/kytConfig', mockKytConfig);
+
+const logger = require('../../cli/logger');
 
 const babel = require('../babel');
 
 describe('babel', () => {
   beforeEach(() => {
-    kytConfig().modifyBabelConfig.mockClear();
+    modifyBabelConfig.mockClear();
+    global.process.exit = jest.fn();
+    Object.keys(logger).forEach(k => logger[k].mockClear());
+  });
+
+  it('does not call process.exit or logger.error on a successful run', () => {
+    babel();
+    expect(logger.error.mock.calls.length).toBe(0);
+    expect(global.process.exit.mock.calls.length).toBe(0);
   });
 
   it('sets flags', () => {
@@ -46,6 +58,7 @@ describe('babel', () => {
   it('calls kytConfig\'s modifyBabelConfig', () => {
     const opts = {};
     babel(opts);
+    const kytConfig = require('../../utils/kytConfig');
     const config = kytConfig();
     expect(config.modifyBabelConfig).toBeCalled();
     expect(config.modifyBabelConfig.mock.calls[0][0]).toEqual(Object.assign({}, stubBabelrc, {
@@ -56,4 +69,12 @@ describe('babel', () => {
     }));
     expect(config.modifyBabelConfig.mock.calls[0][1]).toBe(opts);
   });
+
+  it('logs an error and exits the process if modifyBabelConfig throws', () => {
+    const err = new Error('oh no');
+    modifyBabelConfig.mockImplementationOnce(() => { throw err; });
+    babel();
+    expect(logger.error).toBeCalledWith('Error in your kyt.config.js modifyBabelConfig():', err);
+    expect(global.process.exit).toBeCalledWith(1);
+  });
 });
diff --git a/utils/__mocks__/kytConfig.js b/utils/__mocks__/kytConfig.js
deleted file mode 100644
index cb4dd8d00..000000000
--- a/utils/__mocks__/kytConfig.js
+++ /dev/null
@@ -1,6 +0,0 @@
-const modifyBabelConfig = jest.fn(c => c);
-
-module.exports = () => ({
-  // TODO add more to this mock (this is all we need for now)
-  modifyBabelConfig,
-});

From 835f0a38f942b16bacd5a4f0dd0e11203a359325 Mon Sep 17 00:00:00 2001
From: Jared McDonald <jared.r.mcdonald@gmail.com>
Date: Sat, 8 Oct 2016 15:19:37 -0400
Subject: [PATCH 06/12] improve expectation readability

---
 config/__tests__/babel.test.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/config/__tests__/babel.test.js b/config/__tests__/babel.test.js
index 970584851..e975f3c8e 100644
--- a/config/__tests__/babel.test.js
+++ b/config/__tests__/babel.test.js
@@ -33,8 +33,8 @@ describe('babel', () => {
 
   it('does not call process.exit or logger.error on a successful run', () => {
     babel();
-    expect(logger.error.mock.calls.length).toBe(0);
-    expect(global.process.exit.mock.calls.length).toBe(0);
+    expect(logger.error).not.toBeCalled();
+    expect(global.process.exit).not.toBeCalled();
   });
 
   it('sets flags', () => {

From 3b57e118cd43f857323dd15ccec8bc00c58b034c Mon Sep 17 00:00:00 2001
From: Jared McDonald <jared.r.mcdonald@gmail.com>
Date: Sat, 8 Oct 2016 15:30:19 -0400
Subject: [PATCH 07/12] fix double call of modifyBabelConfig in test
 preprocessor

---
 utils/jest/preprocessor.js | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/utils/jest/preprocessor.js b/utils/jest/preprocessor.js
index 700e09f99..8b9d1a621 100644
--- a/utils/jest/preprocessor.js
+++ b/utils/jest/preprocessor.js
@@ -1,12 +1,10 @@
-const babel = require('../../config/babel')();
 const babelJest = require('babel-jest');
-const config = require('../kytConfig')();
 
 const options = {
   type: 'test',
   environment: 'test',
 };
 
-const babelConfigForJest = config.modifyBabelConfig(babel, options);
+const babelConfigForJest = require('../../config/babel')(options);
 
 module.exports = babelJest.createTransformer(babelConfigForJest);

From 5e3dad7debbdf566f95ba80762d0ec4006e8024c Mon Sep 17 00:00:00 2001
From: Jared McDonald <jared.r.mcdonald@gmail.com>
Date: Sat, 8 Oct 2016 15:41:23 -0400
Subject: [PATCH 08/12] adds test for utils/jest/preprocessor

---
 utils/jest/__tests__/preprocessor.test.js | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 utils/jest/__tests__/preprocessor.test.js

diff --git a/utils/jest/__tests__/preprocessor.test.js b/utils/jest/__tests__/preprocessor.test.js
new file mode 100644
index 000000000..d3636b065
--- /dev/null
+++ b/utils/jest/__tests__/preprocessor.test.js
@@ -0,0 +1,23 @@
+const fakeTransformer = {};
+
+jest.setMock('babel-jest', {
+  createTransformer: jest.fn(() => fakeTransformer),
+});
+const babelJest = require('babel-jest');
+
+const fakeBabelResult = {};
+
+jest.setMock('../../../config/babel', jest.fn(() => fakeBabelResult));
+const babel = require('../../../config/babel');
+
+describe('preprocessor', () => {
+  it('calls the babel utility and babel-jest\'s createTransformer', () => {
+    const preprocessor = require('../preprocessor'); // eslint-disable-line global-require
+    expect(preprocessor).toBe(fakeTransformer);
+    expect(babel.mock.calls[0][0]).toEqual({
+      type: 'test',
+      environment: 'test',
+    });
+    expect(babelJest.createTransformer).toBeCalledWith(fakeBabelResult);
+  });
+});

From 5c516591ad13a89c416971550bb30e1f96502335 Mon Sep 17 00:00:00 2001
From: Jared McDonald <jared.r.mcdonald@gmail.com>
Date: Sat, 8 Oct 2016 15:43:12 -0400
Subject: [PATCH 09/12] add assertion for the addition of default identity
 function in kytConfig base

---
 utils/__tests__/kytConfig.test.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/utils/__tests__/kytConfig.test.js b/utils/__tests__/kytConfig.test.js
index e9da562cc..a8c9b85b1 100644
--- a/utils/__tests__/kytConfig.test.js
+++ b/utils/__tests__/kytConfig.test.js
@@ -30,6 +30,7 @@ describe('kytConfig', () => {
     expect(logger.info).toBeCalled();
     expect(typeof config.modifyWebpackConfig).toBe('function');
     expect(typeof config.modifyJestConfig).toBe('function');
+    expect(typeof config.modifyBabelConfig).toBe('function');
     expect(() => {
       config.productionPublicPath = 'frozen!';
     }).toThrow();

From bb9c7be523ba95d73e26804507c4fbd33e1f4ac2 Mon Sep 17 00:00:00 2001
From: Jared McDonald <jared.r.mcdonald@gmail.com>
Date: Sat, 8 Oct 2016 15:45:22 -0400
Subject: [PATCH 10/12] don't modify this comment anymore

---
 utils/buildConfigs.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/utils/buildConfigs.js b/utils/buildConfigs.js
index fdf958b97..49d7d918a 100644
--- a/utils/buildConfigs.js
+++ b/utils/buildConfigs.js
@@ -47,7 +47,7 @@ module.exports = (config, environment = 'development') => {
   clientConfig = merge.smart(baseConfig(clientOptions), clientConfig(clientOptions));
   serverConfig = merge.smart(baseConfig(serverOptions), serverConfig(serverOptions));
 
-  // Modify via userland webpack config
+  // Modify via userland config
   try {
     clientConfig = config.modifyWebpackConfig(clone(clientConfig), clientOptions);
     serverConfig = config.modifyWebpackConfig(clone(serverConfig), serverOptions);

From b789da3fe6021691deebad42d99f3c7d97fc3075 Mon Sep 17 00:00:00 2001
From: Jared McDonald <jared.r.mcdonald@gmail.com>
Date: Sat, 8 Oct 2016 16:02:55 -0400
Subject: [PATCH 11/12] add debug option to log out merged babelrc

---
 config/__tests__/babel.test.js | 16 +++++++++++++++-
 config/babel.js                | 10 ++++++++--
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/config/__tests__/babel.test.js b/config/__tests__/babel.test.js
index e975f3c8e..56cd7c981 100644
--- a/config/__tests__/babel.test.js
+++ b/config/__tests__/babel.test.js
@@ -17,7 +17,7 @@ jest.setMock('path', {
 });
 
 const modifyBabelConfig = jest.fn(c => c);
-const mockKytConfig = () => ({ modifyBabelConfig });
+const mockKytConfig = jest.fn(() => ({ modifyBabelConfig }));
 jest.setMock('../../utils/kytConfig', mockKytConfig);
 
 const logger = require('../../cli/logger');
@@ -27,6 +27,7 @@ const babel = require('../babel');
 describe('babel', () => {
   beforeEach(() => {
     modifyBabelConfig.mockClear();
+    mockKytConfig.mockClear();
     global.process.exit = jest.fn();
     Object.keys(logger).forEach(k => logger[k].mockClear());
   });
@@ -77,4 +78,17 @@ describe('babel', () => {
     expect(logger.error).toBeCalledWith('Error in your kyt.config.js modifyBabelConfig():', err);
     expect(global.process.exit).toBeCalledWith(1);
   });
+
+  it('does not log out merged config if config.debug is falsy', () => {
+    babel();
+    expect(logger.debug).not.toBeCalled();
+  });
+
+  it('logs out the merged config if config.debug is truthy', () => {
+    mockKytConfig.mockImplementationOnce(() => ({ debug: true, modifyBabelConfig }));
+    babel();
+    expect(logger.debug).toBeCalled();
+    expect(typeof logger.debug.mock.calls[0][0]).toBe('string');
+    expect(typeof logger.debug.mock.calls[0][1]).toBe('object');
+  });
 });
diff --git a/config/babel.js b/config/babel.js
index 6ebb8adc1..1f106f031 100644
--- a/config/babel.js
+++ b/config/babel.js
@@ -1,6 +1,6 @@
 const path = require('path');
 const fs = require('fs');
-const config = require('../utils/kytConfig')();
+const getKytConfig = require('../utils/kytConfig');
 const logger = require('../cli/logger');
 
 // Uses require.resolve to add the full paths to all of the plugins
@@ -18,6 +18,8 @@ const resolvePluginsPresets = (babelGroup) => {
 };
 
 module.exports = (options) => {
+  const config = getKytConfig();
+
   // Create the babelrc query for the babel loader.
   const babelrc = JSON.parse(fs.readFileSync(path.resolve(__dirname, '../.babelrc'), 'utf8'));
   babelrc.babelrc = false;
@@ -30,7 +32,11 @@ module.exports = (options) => {
 
   // modify via userland kytConfig's `modifyBabelConfig`
   try {
-    return config.modifyBabelConfig(babelrc, options);
+    const mergedBabelrc = config.modifyBabelConfig(babelrc, options);
+    if (config.debug) {
+      logger.debug('Merged babel configuration:', mergedBabelrc);
+    }
+    return mergedBabelrc;
   } catch (error) {
     logger.error('Error in your kyt.config.js modifyBabelConfig():', error);
     // return to satisfy eslint `consistent-return` rule

From 52965aa6742192659ca0111dd7f868685619aa3f Mon Sep 17 00:00:00 2001
From: Jared McDonald <jared.r.mcdonald@gmail.com>
Date: Sat, 8 Oct 2016 20:38:36 -0400
Subject: [PATCH 12/12] merged -> modified

---
 config/babel.js | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/config/babel.js b/config/babel.js
index 1f106f031..100c6be2c 100644
--- a/config/babel.js
+++ b/config/babel.js
@@ -30,13 +30,13 @@ module.exports = (options) => {
   }
   Object.keys(babelrc.env || {}).forEach(env => resolvePluginsPresets(babelrc.env[env]));
 
-  // modify via userland kytConfig's `modifyBabelConfig`
   try {
-    const mergedBabelrc = config.modifyBabelConfig(babelrc, options);
+    // modify via userland kytConfig's `modifyBabelConfig`
+    const modifiedBabelrc = config.modifyBabelConfig(babelrc, options);
     if (config.debug) {
-      logger.debug('Merged babel configuration:', mergedBabelrc);
+      logger.debug('Modified babel configuration:', modifiedBabelrc);
     }
-    return mergedBabelrc;
+    return modifiedBabelrc;
   } catch (error) {
     logger.error('Error in your kyt.config.js modifyBabelConfig():', error);
     // return to satisfy eslint `consistent-return` rule