Merge pull request #940 from square/jakew/skip-name-message/2019-09-26

Point at the offending name when failing on unknown

moshi/src/main/java/com/squareup/moshi/JsonUtf8Reader.java

@@ -586,7 +586,10 @@ final class JsonUtf8Reader extends JsonReader {
 
   @Override public void skipName() throws IOException {
     if (failOnUnknown) {
-      throw new JsonDataException("Cannot skip unexpected " + peek() + " at " + getPath());
+      // Capture the peeked value before nextName() since it will reset its value.
+      Token peeked = peek();
+      nextName(); // Move the path forward onto the offending name.
+      throw new JsonDataException("Cannot skip unexpected " + peeked + " at " + getPath());
     }
     int p = peeked;
     if (p == PEEKED_NONE) {

moshi/src/main/java/com/squareup/moshi/JsonValueReader.java

@@ -167,7 +167,10 @@ final class JsonValueReader extends JsonReader {
 
   @Override public void skipName() throws IOException {
     if (failOnUnknown) {
-      throw new JsonDataException("Cannot skip unexpected " + peek() + " at " + getPath());
+      // Capture the peeked value before nextName() since it will reset its value.
+      Token peeked = peek();
+      nextName(); // Move the path forward onto the offending name.
+      throw new JsonDataException("Cannot skip unexpected " + peeked + " at " + getPath());
     }
 
     Map.Entry<?, ?> peeked = require(Map.Entry.class, Token.NAME);

moshi/src/test/java/com/squareup/moshi/JsonReaderTest.java

@@ -972,6 +972,20 @@ public final class JsonReaderTest {
     reader.endObject();
   }
 
+  @Test public void skipNameFailUnknown() throws IOException {
+    JsonReader reader = newReader("{\"a\":1,\"b\":2}");
+    reader.setFailOnUnknown(true);
+    reader.beginObject();
+    assertEquals("a", reader.nextName());
+    assertEquals(1, reader.nextInt());
+    try {
+      reader.skipName();
+      fail();
+    } catch (JsonDataException e) {
+      assertThat(e).hasMessage("Cannot skip unexpected NAME at $.b");
+    }
+  }
+
   @Test public void skipNameOnValueFails() throws IOException {
     JsonReader reader = newReader("1");
     try {

moshi/src/test/java/com/squareup/moshi/MoshiTest.java

@@ -925,7 +925,7 @@ public final class MoshiTest {
       adapter.fromJson("{\"diameter\":5,\"crust\":\"thick\",\"extraCheese\":true}");
       fail();
     } catch (JsonDataException expected) {
-      assertThat(expected).hasMessage("Cannot skip unexpected NAME at $.diameter");
+      assertThat(expected).hasMessage("Cannot skip unexpected NAME at $.crust");
     }
   }