Enforcing that the manifest keys NEVER start with "/"

Author: weaverryan

lib/WebpackConfig.js

@@ -107,6 +107,18 @@ class WebpackConfig {
     }
 
     setManifestKeyPrefix(manifestKeyPrefix) {
+        /*
+         * Normally, we make sure that the manifest keys don't start
+         * with an opening "/" ever... for consistency. If you need
+         * to manually specify the manifest key (e.g. because you're
+         * publicPath is absolute), we're *still* adding this restriction,
+         * to help avoid a user accidentally adding an opening "/"
+         * and changing their keys from what they looked like before.
+         */
+        if (manifestKeyPrefix.indexOf('/') === 0) {
+            throw new Error(`For consistency, the value passed to setManifestKeyPrefix() cannot start with "/". Try setManifestKeyPrefix('${manifestKeyPrefix.replace(/^\//, '')}') instead.`);
+        }
+
         // guarantee a single trailing slash, except for blank strings
         if (manifestKeyPrefix !== '') {
             manifestKeyPrefix = manifestKeyPrefix.replace(/\/$/, '');

test/WebpackConfig.js

@@ -148,10 +148,10 @@ describe('WebpackConfig object', () => {
 
         it('You can set it!', () => {
             const config = createConfig();
-            config.setManifestKeyPrefix('/foo');
+            config.setManifestKeyPrefix('foo');
 
             // trailing slash added
-            expect(config.manifestKeyPrefix).to.equal('/foo/');
+            expect(config.manifestKeyPrefix).to.equal('foo/');
         });
 
         it('You can set it blank', () => {
@@ -161,6 +161,14 @@ describe('WebpackConfig object', () => {
             // trailing slash not added
             expect(config.manifestKeyPrefix).to.equal('');
         });
+
+        it('You cannot use an opening slash', () => {
+            const config = createConfig();
+
+            expect(() => {
+                config.setManifestKeyPrefix('/foo/');
+            }).to.throw('the value passed to setManifestKeyPrefix() cannot start with "/"');
+        });
     });
 
     describe('addEntry', () => {