diff --git a/test/form/custom-module-context-function/_config.js b/test/form/custom-module-context-function/_config.js
new file mode 100644
index 0000000..c15118e
--- /dev/null
+++ b/test/form/custom-module-context-function/_config.js
@@ -0,0 +1,8 @@
+module.exports = {
+	description: 'allows custom module-specific context with a function option',
+	options: {
+		moduleContext ( id ) {
+			return /main\.js$/.test( id ) ? 'lolwut' : 'undefined';
+		}
+	}
+};
diff --git a/test/form/custom-module-context-function/_expected/amd.js b/test/form/custom-module-context-function/_expected/amd.js
new file mode 100644
index 0000000..9274799
--- /dev/null
+++ b/test/form/custom-module-context-function/_expected/amd.js
@@ -0,0 +1,7 @@
+define(function () { 'use strict';
+
+	undefined.prop = 'nope';
+
+	lolwut.prop = '???';
+
+});
diff --git a/test/form/custom-module-context-function/_expected/cjs.js b/test/form/custom-module-context-function/_expected/cjs.js
new file mode 100644
index 0000000..35a5b08
--- /dev/null
+++ b/test/form/custom-module-context-function/_expected/cjs.js
@@ -0,0 +1,5 @@
+'use strict';
+
+undefined.prop = 'nope';
+
+lolwut.prop = '???';
diff --git a/test/form/custom-module-context-function/_expected/es.js b/test/form/custom-module-context-function/_expected/es.js
new file mode 100644
index 0000000..a6903e0
--- /dev/null
+++ b/test/form/custom-module-context-function/_expected/es.js
@@ -0,0 +1,3 @@
+undefined.prop = 'nope';
+
+lolwut.prop = '???';
diff --git a/test/form/custom-module-context-function/_expected/iife.js b/test/form/custom-module-context-function/_expected/iife.js
new file mode 100644
index 0000000..7926fe6
--- /dev/null
+++ b/test/form/custom-module-context-function/_expected/iife.js
@@ -0,0 +1,8 @@
+(function () {
+	'use strict';
+
+	undefined.prop = 'nope';
+
+	lolwut.prop = '???';
+
+}());
diff --git a/test/form/custom-module-context-function/_expected/umd.js b/test/form/custom-module-context-function/_expected/umd.js
new file mode 100644
index 0000000..22fa605
--- /dev/null
+++ b/test/form/custom-module-context-function/_expected/umd.js
@@ -0,0 +1,11 @@
+(function (global, factory) {
+	typeof exports === 'object' && typeof module !== 'undefined' ? factory() :
+	typeof define === 'function' && define.amd ? define(factory) :
+	(factory());
+}(this, (function () { 'use strict';
+
+	undefined.prop = 'nope';
+
+	lolwut.prop = '???';
+
+})));
diff --git a/test/form/custom-module-context-function/foo.js b/test/form/custom-module-context-function/foo.js
new file mode 100644
index 0000000..a5a991d
--- /dev/null
+++ b/test/form/custom-module-context-function/foo.js
@@ -0,0 +1 @@
+this.prop = 'nope';
diff --git a/test/form/custom-module-context-function/main.js b/test/form/custom-module-context-function/main.js
new file mode 100644
index 0000000..1323b68
--- /dev/null
+++ b/test/form/custom-module-context-function/main.js
@@ -0,0 +1,2 @@
+import './foo.js';
+this.prop = '???';
diff --git a/test/test.js b/test/test.js
index aa2bbbb..f6b36c6 100644
--- a/test/test.js
+++ b/test/test.js
@@ -316,6 +316,8 @@ describe( 'rollup', function () {
 
 				PROFILES.forEach( profile => {
 					it( 'generates ' + profile.format, () => {
+						process.chdir( FORM + '/' + dir );
+
 						return createBundle().then( bundle => {
 							const options = extend( {}, config.options, {
 								dest: FORM + '/' + dir + '/_actual/' + profile.format + '.js',