fix(preProcessPattern): throw an {Error} if pattern.from is empty or undefined

src/preProcessPattern.js

@@ -14,6 +14,9 @@ export default function preProcessPattern(globalRef, pattern) {
     pattern = typeof pattern === 'string' ? {
         from: pattern
     } : Object.assign({}, pattern);
+    if (pattern.from === '') {
+        throw new Error('[copy-webpack-plugin] path "from" cannot be empty string');
+    }
     pattern.to = pattern.to || '';
     pattern.context = pattern.context || context;
     if (!path.isAbsolute(pattern.context)) {

tests/index.js

@@ -236,6 +236,16 @@ describe('apply function', () => {
 
             expect(createPluginWithNull).to.throw(Error);
         });
+
+        it('throws an error if the "from" path is an empty string', () => {
+            const createPluginWithNull = () => {
+                CopyWebpackPlugin({
+                    from: ''
+                });
+            };
+
+            expect(createPluginWithNull).to.throw(Error);
+        });
     });
 
     describe('with glob in from', () => {
@@ -1615,7 +1625,7 @@ describe('apply function', () => {
                         patterns: [{
                             from: '.'
                         }]
-    
+
                     })
                     .then(done)
                     .catch(done);