1 files changed, 132 insertions, 0 deletions
diff --git a/document/src/test/java/com/yahoo/document/json/LazyTokenBufferTest.java b/document/src/test/java/com/yahoo/document/json/LazyTokenBufferTest.java
new file mode 100644
index 00000000000..3ed2ed531c3
--- /dev/null
+++ b/document/src/test/java/com/yahoo/document/json/LazyTokenBufferTest.java
@@ -0,0 +1,132 @@
+package com.yahoo.document.json;
+
+import com.fasterxml.jackson.core.JsonFactory;
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonToken;
+import com.yahoo.document.json.TokenBuffer.Token;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.util.function.Supplier;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+/**
+ * @author jonmv
+ */
+public class LazyTokenBufferTest {
+
+    @Test
+    public void testBuffer() throws IOException {
+        String json = """
+                      {
+                        "fields": {
+                          "foo": "bar",
+                          "baz": [1, 2, 3],
+                          "quu": { "qux": null }
+                        }
+                      }""";
+        JsonParser parser = new JsonFactory().createParser(json);
+        parser.nextValue();
+        parser.nextValue();
+        assertEquals(JsonToken.START_OBJECT, parser.currentToken());
+        assertEquals("fields", parser.currentName());
+
+        // Peeking through the buffer doesn't change nesting.
+        LazyTokenBuffer buffer = new LazyTokenBuffer(parser);
+        assertEquals(JsonToken.START_OBJECT, buffer.current());
+        assertEquals("fields", buffer.currentName());
+        assertEquals(1, buffer.nesting());
+
+        Supplier<Token> lookahead = buffer.lookahead();
+        Token peek = lookahead.get();
+        assertEquals(JsonToken.VALUE_STRING, peek.token);
+        assertEquals("foo", peek.name);
+        assertEquals("bar", peek.text);
+        assertEquals(1, buffer.nesting());
+
+        peek = lookahead.get();
+        assertEquals(JsonToken.START_ARRAY, peek.token);
+        assertEquals("baz", peek.name);
+        assertEquals(1, buffer.nesting());
+
+        peek = lookahead.get();
+        assertEquals(JsonToken.VALUE_NUMBER_INT, peek.token);
+        assertEquals("1", peek.text);
+
+        peek = lookahead.get();
+        assertEquals(JsonToken.VALUE_NUMBER_INT, peek.token);
+        assertEquals("2", peek.text);
+
+        peek = lookahead.get();
+        assertEquals(JsonToken.VALUE_NUMBER_INT, peek.token);
+        assertEquals("3", peek.text);
+
+        peek = lookahead.get();
+        assertEquals(JsonToken.END_ARRAY, peek.token);
+        assertEquals(1, buffer.nesting());
+
+        peek = lookahead.get();
+        assertEquals(JsonToken.START_OBJECT, peek.token);
+        assertEquals("quu", peek.name);
+        assertEquals(1, buffer.nesting());
+
+        peek = lookahead.get();
+        assertEquals(JsonToken.VALUE_NULL, peek.token);
+        assertEquals("qux", peek.name);
+
+        peek = lookahead.get();
+        assertEquals(JsonToken.END_OBJECT, peek.token);
+        assertEquals(1, buffer.nesting());
+
+        peek = lookahead.get();
+        assertEquals(JsonToken.END_OBJECT, peek.token);
+        assertEquals(1, buffer.nesting());
+
+        peek = lookahead.get();
+        assertNull(peek);
+
+        // Parser is now at the end.
+        assertEquals(JsonToken.END_OBJECT, parser.nextToken());
+        assertNull(parser.nextToken());
+
+        // Repeat iterating through the buffer, this time advancing it, and see that nesting changes.
+        assertEquals(JsonToken.VALUE_STRING, buffer.next());
+        assertEquals("foo", buffer.currentName());
+        assertEquals("bar", buffer.currentText());
+        assertEquals(1, buffer.nesting());
+
+        assertEquals(JsonToken.START_ARRAY, buffer.next());
+        assertEquals("baz", buffer.currentName());
+        assertEquals(2, buffer.nesting());
+
+        assertEquals(JsonToken.VALUE_NUMBER_INT, buffer.next());
+        assertEquals("1", buffer.currentText());
+
+        assertEquals(JsonToken.VALUE_NUMBER_INT, buffer.next());
+        assertEquals("2", buffer.currentText());
+
+        assertEquals(JsonToken.VALUE_NUMBER_INT, buffer.next());
+        assertEquals("3", buffer.currentText());
+
+        assertEquals(JsonToken.END_ARRAY, buffer.next());
+        assertEquals(1, buffer.nesting());
+
+        assertEquals(JsonToken.START_OBJECT, buffer.next());
+        assertEquals("quu", buffer.currentName());
+        assertEquals(2, buffer.nesting());
+
+        assertEquals(JsonToken.VALUE_NULL, buffer.next());
+        assertEquals("qux", buffer.currentName());
+
+        assertEquals(JsonToken.END_OBJECT, buffer.next());
+        assertEquals(1, buffer.nesting());
+
+        assertEquals(JsonToken.END_OBJECT, buffer.next());
+        assertEquals(0, buffer.nesting());
+
+        assertNull(buffer.next());
+    }
+
+}