Improved test for HTTP chunking

Also fixed a bug in the error handling where a `FailedRequest` was constructed and populated, but it was not actually passed into the `FailedRequestException`, thereby causing a null-pointer error when certain parts of the `FailedRequestException` were added.

Author: rjrudin

marklogic-client-api/src/main/java/com/marklogic/client/impl/OkHttpServices.java

@@ -4594,22 +4594,27 @@ private <U extends OkHttpResultIterator> U makeResults(
     }
     List<BodyPart> partList = getPartList(entity);
 
+    String mlErrorCode = null;
+    String mlErrorMessage = null;
     try {
-        Headers trailer = response.trailers();
-        String code = trailer.get("ml-error-code");
-        String msg = trailer.get("ml-error-message");
-        String sha = trailer.get("ml-content-sha256");
-
-        if (code != null && !"N/A".equals(code)) {
-            FailedRequest failure = new FailedRequest();
-            failure.setMessageString(code);
-            failure.setStatusString(msg);
-            throw new FailedRequestException("failed to " + operation + " "
-                    + entityType + " at rows" + ": " + code + ", " + msg);
-        }
+        Headers trailers = response.trailers();
+        mlErrorCode = trailers.get("ml-error-code");
+        mlErrorMessage = trailers.get("ml-error-message");
     } catch (IOException e) {
-        throw new RuntimeException("No trailer header in repsonse");
+        // This does not seem worthy of causing the entire operation to fail; we also don't expect this to occur, as it
+        // should only occur due to a programming error where the response body has already been consumed
+        logger.warn("Unexpected IO error while getting HTTP response trailers: " + e.getMessage());
     }
+
+    if (mlErrorCode != null && !"N/A".equals(mlErrorCode)) {
+      FailedRequest failure = new FailedRequest();
+      failure.setMessageString(mlErrorCode);
+      failure.setStatusString(mlErrorMessage);
+      failure.setStatusCode(500);
+      throw new FailedRequestException("failed to " + operation + " "
+          + entityType + " at rows" + ": " + mlErrorCode + ", " + mlErrorMessage, failure);
+    }
+
     Closeable closeable = response;
     return makeResults(constructor, reqlog, operation, entityType, partList, response, closeable);
   }

marklogic-client-api/src/test/java/com/marklogic/client/test/rows/RowManagerTest.java

@@ -16,11 +16,7 @@
 package com.marklogic.client.test.rows;
 
 import static org.custommonkey.xmlunit.XMLAssert.assertXMLEqual;
-import static org.junit.Assert.assertArrayEquals;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.*;
 
 import java.io.IOException;
 import java.io.LineNumberReader;
@@ -40,6 +36,7 @@
 import javax.xml.xpath.XPathExpressionException;
 
 import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.marklogic.client.FailedRequestException;
 import com.marklogic.client.datamovement.DataMovementManager;
 import com.marklogic.client.datamovement.WriteBatcher;
 import com.marklogic.client.io.*;
@@ -527,27 +524,33 @@ public void testSQL0Result() {
     assertEquals("", exception);
   }
 
+  /**
+   * This test was added to take advantage of MarkLogic 11's support for HTTP chunking. It is expected that when calls
+   * are made to /v1/rows, the TE and ML-Check-ML11-Headers headers will be added, thus triggering HTTP chunking in the
+   * server. The SQL query in this test is designed to produce an error for the "last" musician of the 4 in the test
+   * database. OkHttpServices is then expected to check for the special MarkLogic trailers in the HTTP response -
+   * ml-error-code and ml-error-message. And then the end result is that a FailedRequestException is expected.
+   *
+   * You can verify this test works by commenting out the sections in OkHttpServices that check for the special
+   * MarkLogic trailers in the HTTP response, and/or commenting out the two places where the TE/ML-Check-ML11-Headers
+   * headers are sent.
+   */
   @Test
-  public void testSQLException() {
+  public void testMarklogicHeadersProduceExpectedError() {
     if (!Common.markLogicIsVersion11OrHigher()) {
       return;
     }
 
     RowManager rowMgr = Common.client.newRowManager();
-    PlanBuilder p = rowMgr.newPlanBuilder();
-    PlanBuilder.ExportablePlan builtPlan =
-        p.fromSql("select case when lastName = 'Davis' then fn_error(fn_qname('', 'SQL-TABLENOTFOUND'), 'Internal Server Error') end, opticUnitTest.musician.* from (select * from opticUnitTest.musician order by lastName)");
-    String exception = "";
-    int rowNum = 0;
-    try {
-      for (RowRecord row: rowMgr.resultRows(builtPlan)) {
-        rowNum++;
-      }
-    } catch (Exception e) {
-      exception = e.toString();
-    }
-    assertEquals(0, rowNum);
-    assertEquals("com.marklogic.client.FailedRequestException: failed to apply resource at rows: SQL-TABLENOTFOUND, Internal Server Error", exception);
+    PlanBuilder.ExportablePlan builtPlan = rowMgr.newPlanBuilder()
+        .fromSql("select case when lastName = 'Davis' then fn_error(fn_qname('', 'SQL-TABLENOTFOUND'), 'Internal Server Error') end, " +
+            "opticUnitTest.musician.* from (select * from opticUnitTest.musician order by lastName)");
+
+    FailedRequestException ex = assertThrows(FailedRequestException.class, () -> rowMgr.resultRows(builtPlan));
+    assertEquals(500, ex.getServerStatusCode());
+    assertEquals("SQL-TABLENOTFOUND", ex.getServerMessage());
+    assertEquals("Local message: failed to apply resource at rows: SQL-TABLENOTFOUND, Internal Server Error. Server Message: SQL-TABLENOTFOUND",
+        ex.getMessage());
   }
 
   @Test