[Chromedriver] Add ability to merge capabilities to make chromedriver closer...

[Chromedriver] Add ability to merge capabilities to make chromedriver closer to being w3c compliant.

This is built on yash's previous work.
w3c standard: https://w3c.github.io/webdriver/webdriver-spec.html#processing-capabilities

Change-Id: I9b2f49c0f2ebff59fd5b053c2d8b9b99a95aabe5

BUG=chromedriver:1740

Change-Id: I9b2f49c0f2ebff59fd5b053c2d8b9b99a95aabe5
Reviewed-on: https://chromium-review.googlesource.com/562377Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Jonathon Kereliuk <kereliuk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488663}

chrome/test/chromedriver/session_commands.cc

@@ -11,6 +11,7 @@
 #include "base/callback.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"  // For CHECK macros.
+#include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/strings/string_util.h"
 #include "base/synchronization/lock.h"
@@ -189,13 +190,39 @@ Status InitSessionHelper(const InitSessionParams& bound_params,
   session->driver_log.reset(
       new WebDriverLog(WebDriverLog::kDriverType, Log::kAll));
   const base::DictionaryValue* desired_caps;
+  base::DictionaryValue merged_caps;
+
   bool w3c_capability = false;
   if (params.GetDictionary("capabilities.alwaysMatch", &desired_caps) &&
       (desired_caps->GetBoolean("goog:chromeOptions.w3c", &w3c_capability) ||
        desired_caps->GetBoolean("chromeOptions.w3c", &w3c_capability)) &&
       w3c_capability) {
-    // TODO(johnchen): Handle capabilities.firstMatch.
     session->w3c_compliant = true;
+    // TODO(johnchen): Handle capabilities.firstMatch. Currently, we're just
+    // merging, not validating or matching as per the spec.
+    const base::ListValue* first_match_list;
+    std::unique_ptr<base::ListValue> tmp_list;
+    if (!(params.GetList("capabilities.firstMatch", &first_match_list))) {
+      // if no firstMatch, make first_match_list a list with an empty dictionary
+      tmp_list = std::unique_ptr<base::ListValue>(new base::ListValue());
+      std::unique_ptr<base::DictionaryValue> inner(new base::DictionaryValue());
+      tmp_list->Append(std::move(inner));
+      first_match_list = tmp_list.get();
+    }
+    for (size_t i = 0; i < first_match_list->GetSize(); ++i) {
+      const base::DictionaryValue* first_match;
+      if (!first_match_list->GetDictionary(i, &first_match)) {
+        continue;
+      }
+      if (!MergeCapabilities(desired_caps, first_match, &merged_caps)) {
+        return Status(kSessionNotCreatedException, "Invalid capabilities");
+      }
+      if (MatchCapabilities(&merged_caps)) {
+        // If a match is found, we want to use these matched setcapabilities.
+        desired_caps = &merged_caps;
+        break;
+      }
+    }
   } else if (params.GetDictionary("capabilities.desiredCapabilities",
                                   &desired_caps) &&
              (desired_caps->GetBoolean("goog:chromeOptions.w3c",
@@ -260,6 +287,28 @@ Status InitSessionHelper(const InitSessionParams& bound_params,
 
 }  // namespace
 
+bool MergeCapabilities(const base::DictionaryValue* always_match,
+                       const base::DictionaryValue* first_match,
+                       base::DictionaryValue* merged) {
+  CHECK(always_match);
+  CHECK(first_match);
+  CHECK(merged);
+  merged->Clear();
+
+  for (base::DictionaryValue::Iterator it(*first_match); !it.IsAtEnd();
+       it.Advance()) {
+    if (always_match->HasKey(it.key())) {
+      // firstMatch cannot have the same |keys| as alwaysMatch.
+      return false;
+    }
+  }
+
+  // merge the capabilities together since guarenteed no key collisions
+  merged->MergeDictionary(always_match);
+  merged->MergeDictionary(first_match);
+  return true;
+}
+
 bool MatchCapabilities(base::DictionaryValue* capabilities) {
   // attempt to match the capabilities requested to the actual capabilities
   // reject if they don't match
@@ -270,7 +319,6 @@ bool MatchCapabilities(base::DictionaryValue* capabilities) {
       return false;
     }
   }
-
   return true;
 }
 

chrome/test/chromedriver/session_commands.h

@@ -40,6 +40,10 @@ struct InitSessionParams {
   PortManager* port_manager;
 };
 
+bool MergeCapabilities(const base::DictionaryValue* always_match,
+                       const base::DictionaryValue* first_match,
+                       base::DictionaryValue* merged);
+
 bool MatchCapabilities(base::DictionaryValue* capabilities);
 
 // Initializes a session.

chrome/test/chromedriver/session_commands_unittest.cc

@@ -21,6 +21,30 @@
 #include "chrome/test/chromedriver/session.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+TEST(SessionCommandsTest, MergeCapabilities) {
+  base::DictionaryValue primary;
+  primary.SetString("strawberry", "velociraptor");
+  primary.SetString("pear", "unicorn");
+
+  base::DictionaryValue secondary;
+  secondary.SetString("broccoli", "giraffe");
+  secondary.SetString("celery", "hippo");
+  secondary.SetString("eggplant", "elephant");
+
+  base::DictionaryValue merged;
+
+  // key collision should return false
+  ASSERT_FALSE(MergeCapabilities(&primary, &primary, &merged));
+  // non key collision should return true
+  ASSERT_TRUE(MergeCapabilities(&primary, &secondary, &merged));
+
+  merged.Clear();
+  MergeCapabilities(&primary, &secondary, &merged);
+  primary.MergeDictionary(&secondary);
+
+  ASSERT_EQ(primary, merged);
+}
+
 TEST(SessionCommandsTest, FileUpload) {
   Session session("id");
   base::DictionaryValue params;