Bug 1426501 - Change nsIURIMutator to call set spec on cloned URI if …

…available r=mayhemer

Calling SetSpec on an nsIURI object doesn't reinitialize the object, meaning
it's not equivalent with creating a new URI with the same spec. While this
might be counter-intuitive we want to preserve existing behaviour for
the moment.
This change makes BaseURIMutator::InitFromSpec call SetSpec on the existing
cloned URI if available. Otherwise it creates a new one.

MozReview-Commit-ID: LuHVRhBItiP

netwerk/base/nsIURIMutator.idl

@@ -66,8 +66,16 @@ protected:
 
   MOZ_MUST_USE nsresult InitFromSpec(const nsACString& aSpec)
   {
-    RefPtr<T> uri = new T();
-    nsresult rv = uri->SetSpec(aSpec);
+    nsresult rv = NS_OK;
+    RefPtr<T> uri;
+    if (mURI) {
+      // This only works because all other Init methods create a new object
+      mURI.swap(uri);
+    } else {
+      uri = new T();
+    }
+
+    rv = uri->SetSpec(aSpec);
     if (NS_FAILED(rv)) {
       return rv;
     }

netwerk/test/unit/test_URIs.js

@@ -485,8 +485,11 @@ function do_test_mutate_ref(aTest, aSuffix) {
     var specWithSuffix = aTest.spec + aSuffix;
     do_info("testing that setting spec to " +
             specWithSuffix + " and then clearing ref does what we expect");
-    testURI.spec = specWithSuffix;
-    testURI.ref = "";
+
+    testURI = testURI.mutate()
+                     .setSpec(specWithSuffix)
+                     .setRef("")
+                     .finalize();
     do_check_uri_eq(testURI, refURIWithoutSuffix);
     do_check_uri_eqExceptRef(testURI, refURIWithSuffix);
 

netwerk/test/unit/test_URIs2.js

@@ -587,8 +587,10 @@ function do_test_mutate_ref(aTest, aSuffix) {
     var specWithSuffix = aTest.spec + aSuffix;
     do_info("testing that setting spec to " +
             specWithSuffix + " and then clearing ref does what we expect");
-    testURI.spec = specWithSuffix;
-    testURI.ref = "";
+    testURI = testURI.mutate()
+                     .setSpec(specWithSuffix)
+                     .setRef("")
+                     .finalize();
     do_check_uri_eq(testURI, refURIWithoutSuffix);
     do_check_uri_eqExceptRef(testURI, refURIWithSuffix);