add token count test (#662)

src/test/java/com/fasterxml/jackson/dataformat/xml/stream/dos/TokenCountTest.java

@@ -0,0 +1,65 @@
+package com.fasterxml.jackson.dataformat.xml.stream.dos;
+
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.StreamReadConstraints;
+import com.fasterxml.jackson.core.exc.StreamConstraintsException;
+import com.fasterxml.jackson.dataformat.xml.XmlFactory;
+import com.fasterxml.jackson.dataformat.xml.XmlMapper;
+import com.fasterxml.jackson.dataformat.xml.XmlTestBase;
+
+public class TokenCountTest extends XmlTestBase
+{
+    final XmlMapper XML_MAPPER;
+    {
+        final XmlFactory factory = XmlFactory.builder()
+                // token count is only checked when maxTokenCount is set
+                .streamReadConstraints(StreamReadConstraints.builder()
+                        .maxTokenCount(1000)
+                        .build())
+                .build();
+        XML_MAPPER = mapperBuilder(factory).build();
+    }
+
+    public void testTokenCount10() throws Exception
+    {
+        final String XML = createDeepNestedDoc(10);
+        try (JsonParser p = XML_MAPPER.createParser(XML)) {
+            while (p.nextToken() != null) { }
+            assertEquals(31, p.currentTokenCount());
+        }
+    }
+
+    public void testTokenCount100() throws Exception
+    {
+        final String XML = createDeepNestedDoc(100);
+        try (JsonParser p = XML_MAPPER.createParser(XML)) {
+            while (p.nextToken() != null) { }
+            assertEquals(301, p.currentTokenCount());
+        }
+    }
+
+    public void testDeepDoc() throws Exception
+    {
+        final String XML = createDeepNestedDoc(1000);
+        try (JsonParser p = XML_MAPPER.createParser(XML)) {
+            while (p.nextToken() != null) { }
+            fail("expected StreamReadException");
+        } catch (StreamConstraintsException e) {
+            assertTrue(e.getMessage().contains("Token count (1001) exceeds the maximum allowed"));
+        }
+    }
+
+    private String createDeepNestedDoc(final int depth) {
+        StringBuilder sb = new StringBuilder();
+        sb.append("<a>");
+        for (int i = 0; i < depth; i++) {
+            sb.append("<a>");
+        }
+        sb.append("a");
+        for (int i = 0; i < depth; i++) {
+            sb.append("</a>");
+        }
+        sb.append("</a>");
+        return sb.toString();
+    }
+}