get test passing

test/cli/multiple-configs/_config.js

@@ -1,4 +1,10 @@
+const assert = require('assert');
+
 module.exports = {
 	description: 'generates output file when multiple configurations are specified and one build fails',
-	command: 'rollup -c'
+	command: 'rollup -c',
+	error: err => {
+		assert.ok(/Unexpected Exception/.test(err.message));
+		return true;
+	}
 };

test/test.js

@@ -543,8 +543,8 @@ describe( 'rollup', function () {
 					exec( command, {}, ( err, code, stderr ) => {
 						if ( err ) {
 							if ( config.error ) {
-								config.error( err );
-								return done();
+								const shouldContinue = config.error( err );
+								if (!shouldContinue) return done();
 							} else {
 								throw err;
 							}