Handle null and empty paths the same as /

This prevents a NPE when working with the java servlet API, which
returns a null path for requests to the context root (e.g. POST /wd/hub)

Author: jleyba

java/client/src/org/openqa/selenium/remote/http/JsonHttpCommandCodec.java

@@ -12,6 +12,7 @@
 import com.google.common.base.Objects;
 import com.google.common.base.Predicate;
 import com.google.common.base.Splitter;
+import com.google.common.base.Strings;
 import com.google.common.collect.BiMap;
 import com.google.common.collect.FluentIterable;
 import com.google.common.collect.HashBiMap;
@@ -207,7 +208,8 @@ public HttpRequest encode(Command command) {
 
   @Override
   public Command decode(final HttpRequest encodedCommand) {
-    final String path = encodedCommand.getUri();
+    final String path = Strings.isNullOrEmpty(encodedCommand.getUri())
+                        ? "/" : encodedCommand.getUri();
     final ImmutableList<String> parts = ImmutableList.copyOf(PATH_SPLITTER.split(path));
     List<CommandSpec> matchingSpecs = FluentIterable.from(nameToSpec.inverse().keySet())
         .filter(new Predicate<CommandSpec>() {

java/client/test/org/openqa/selenium/remote/http/JsonHttpCommandCodecTest.java

@@ -273,4 +273,68 @@ public void codecRoundTrip() {
     assertThat(decoded.getSessionId(), is(original.getSessionId()));
     assertThat(decoded.getParameters(), is((Map) original.getParameters()));
   }
+
+  @Test
+  public void treatsEmptyPathAsRoot_recognizedCommand() {
+    codec.defineCommand("num", POST, "/");
+
+    byte[] data = "{\"char\":\"水\"}".getBytes(UTF_8);
+    HttpRequest request = new HttpRequest(POST, "");
+    request.setHeader(CONTENT_TYPE, JSON_UTF_8.withoutParameters().toString());
+    request.setHeader(CONTENT_LENGTH, String.valueOf(data.length));
+    request.setContent(data);
+
+    Command command = codec.decode(request);
+    assertThat(command.getName(), is("num"));
+  }
+
+  @Test
+  public void treatsNullPathAsRoot_recognizedCommand() {
+    codec.defineCommand("num", POST, "/");
+
+    byte[] data = "{\"char\":\"水\"}".getBytes(UTF_8);
+    HttpRequest request = new HttpRequest(POST, null);
+    request.setHeader(CONTENT_TYPE, JSON_UTF_8.withoutParameters().toString());
+    request.setHeader(CONTENT_LENGTH, String.valueOf(data.length));
+    request.setContent(data);
+
+    Command command = codec.decode(request);
+    assertThat(command.getName(), is("num"));
+  }
+
+  @Test
+  public void treatsEmptyPathAsRoot_unrecognizedCommand() {
+    codec.defineCommand("num", GET, "/");
+
+    byte[] data = "{\"char\":\"水\"}".getBytes(UTF_8);
+    HttpRequest request = new HttpRequest(POST, "");
+    request.setHeader(CONTENT_TYPE, JSON_UTF_8.withoutParameters().toString());
+    request.setHeader(CONTENT_LENGTH, String.valueOf(data.length));
+    request.setContent(data);
+
+    try {
+      codec.decode(request);
+      fail();
+    } catch (UnsupportedCommandException expected) {
+      // Do nothing.
+    }
+  }
+
+  @Test
+  public void treatsNullPathAsRoot_unrecognizedCommand() {
+    codec.defineCommand("num", GET, "/");
+
+    byte[] data = "{\"char\":\"水\"}".getBytes(UTF_8);
+    HttpRequest request = new HttpRequest(POST, null);
+    request.setHeader(CONTENT_TYPE, JSON_UTF_8.withoutParameters().toString());
+    request.setHeader(CONTENT_LENGTH, String.valueOf(data.length));
+    request.setContent(data);
+
+    try {
+      codec.decode(request);
+      fail();
+    } catch (UnsupportedCommandException expected) {
+      // Do nothing.
+    }
+  }
 }

java/server/src/org/openqa/selenium/remote/server/DriverServlet.java

@@ -21,6 +21,7 @@
 import static java.util.Collections.list;
 
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Strings;
 import com.google.common.base.Supplier;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.io.ByteStreams;
@@ -203,9 +204,13 @@ protected void handleRequest(
 
   private static HttpRequest createInternalRequest(HttpServletRequest servletRequest)
       throws IOException {
+    String path = servletRequest.getPathInfo();
+    if (Strings.isNullOrEmpty(path)) {
+      path = "/";
+    }
     HttpRequest request = new HttpRequest(
         HttpMethod.valueOf(servletRequest.getMethod().toUpperCase()),
-        servletRequest.getPathInfo());
+        path);
 
     @SuppressWarnings("unchecked")
     Enumeration<String> headerNames = servletRequest.getHeaderNames();

java/server/test/org/openqa/selenium/remote/server/DriverServletTest.java

@@ -172,6 +172,20 @@ public void doesNotRedirectForNewSessionsRequestedViaCrossDomainRpc()
     assertTrue(value.getBoolean(CapabilityType.VERSION));
   }
 
+  @Test
+  public void handlesInvalidCommandsToRootOfDriverService()
+      throws IOException, ServletException, JSONException {
+    // Command path will be null in servlet API when request is to the context root (e.g. /wd/hub).
+    FakeHttpServletResponse response = sendCommand("POST", null, new JSONObject());
+    assertEquals(500, response.getStatus());
+
+    JSONObject jsonResponse = new JSONObject(response.getBody());
+    assertEquals(ErrorCodes.UNHANDLED_ERROR, jsonResponse.getInt("status"));
+
+    JSONObject value = jsonResponse.getJSONObject("value");
+    assertTrue(value.getString("message").startsWith("POST /"));
+  }
+
   private SessionId createSession() throws IOException, ServletException {
     FakeHttpServletResponse response = sendCommand("POST", "/session", null);