fix($location): allow hash fragments with hashPrefix in hash-bang location urls

Previously if there was a hash fragment but no hashPrefix we would throw an error.
Now we assume that the hash-bang path is empty and that the hash is a valid fragment.

This prevents unnecessary exceptions where we clear the hashBang path, say by
navigating back to the base url, where the $browser leaves an empty hash symbol
on the URL to ensure there is no browser reload.

BREAKING CHANGE:

We no longer throw an `ihshprfx` error if the URL after the base path
contains only a hash fragment.  Previously, if the base URL was `http://abc.com/base/`
and the hashPrefix is `!` then trying to parse `http://abc.com/base/#some-fragment`
would have thrown an error. Now we simply assume it is a normal fragment and
that the path is empty, resulting `$location.absUrl() === "http://abc.com/base/#!/#some-fragment"`.

This should not break any applications, but you can no longer rely on receiving the
`ihshprfx` error for paths that have the syntax above. It is actually more similar
to what currently happens for invalid extra paths anyway:  If the base URL
and hashPrfix are set up as above, then `http://abc.com/base/other/path` does not
throw an error but just ignores the extra path: `http://abc.com/base`.

Closes angular#9629
Closes angular#9635
Closes angular#10228

Author: petebacondarwin

src/ng/location.js

@@ -183,16 +183,25 @@ function LocationHashbangUrl(appBase, hashPrefix) {
    */
   this.$$parse = function(url) {
     var withoutBaseUrl = beginsWith(appBase, url) || beginsWith(appBaseNoFile, url);
-    var withoutHashUrl = withoutBaseUrl.charAt(0) == '#'
-        ? beginsWith(hashPrefix, withoutBaseUrl)
-        : (this.$$html5)
-          ? withoutBaseUrl
-          : '';
-
-    if (!isString(withoutHashUrl)) {
-      throw $locationMinErr('ihshprfx', 'Invalid url "{0}", missing hash prefix "{1}".', url,
-          hashPrefix);
+    var withoutHashUrl;
+
+    if (withoutBaseUrl.charAt(0) === '#') {
+
+      // The rest of the url starts with a hash so we have
+      // got either a hashbang path or a plain hash fragment
+      withoutHashUrl = beginsWith(hashPrefix, withoutBaseUrl);
+      if (isUndefined(withoutHashUrl)) {
+        // There was no hashbang prefix so we just have a hash fragment
+        withoutHashUrl = withoutBaseUrl;
+      }
+
+    } else {
+      // There was no hashbang path nor hash fragment:
+      // If we are in HTML5 mode we use what is left as the path;
+      // Otherwise we ignore what is left
+      withoutHashUrl = this.$$html5 ? withoutBaseUrl : '';
     }
+
     parseAppUrl(withoutHashUrl, this);
 
     this.$$path = removeWindowsDriveName(this.$$path, withoutHashUrl, appBase);

test/ng/locationSpec.js

@@ -554,10 +554,24 @@ describe('$location', function() {
     });
 
 
-    it('should throw error when invalid hashbang prefix given', function() {
-      expect(function() {
-        url.$$parse('http://www.server.org:1234/base#/path');
-      }).toThrowMinErr('$location', 'ihshprfx', 'Invalid url "http://www.server.org:1234/base#/path", missing hash prefix "#!".');
+    it('should insert default hashbang if a hash is given with no hashbang prefix', function() {
+
+      url.$$parse('http://www.server.org:1234/base#/path');
+      expect(url.absUrl()).toBe('http://www.server.org:1234/base#!#%2Fpath');
+      expect(url.hash()).toBe('/path');
+      expect(url.path()).toBe('');
+
+      url.$$parse('http://www.server.org:1234/base#');
+      expect(url.absUrl()).toBe('http://www.server.org:1234/base');
+      expect(url.hash()).toBe('');
+      expect(url.path()).toBe('');
+    });
+
+    it('should ignore extra path segments if no hashbang is given', function() {
+      url.$$parse('http://www.server.org:1234/base/extra/path');
+      expect(url.absUrl()).toBe('http://www.server.org:1234/base');
+      expect(url.path()).toBe('');
+      expect(url.hash()).toBe('');
     });