[FLINK-2628] [tests] CoStreamCheckpointingITCase prints a warning when test is inconclusive

The test is inconclusive when the test failure happens before the first checkpoint.

flink-tests/src/test/java/org/apache/flink/test/checkpointing/CoStreamCheckpointingITCase.java

@@ -31,7 +31,6 @@ import org.apache.flink.streaming.api.functions.sink.SinkFunction;
 import org.apache.flink.streaming.api.functions.source.ParallelSourceFunction;
 import org.apache.flink.streaming.api.functions.source.RichSourceFunction;
 import org.apache.flink.util.Collector;
-import org.junit.Assert;
 
 import java.io.IOException;
 import java.util.Random;
@@ -80,21 +79,21 @@ public class CoStreamCheckpointingITCase extends StreamFaultToleranceTestBase {
 				// -------------- first vertex, chained to the source ----------------
 				.filter(new StringRichFilterFunction())
 
-						// -------------- second vertex - the stateful one that also fails ----------------
+				// -------------- second vertex - stateful ----------------
 				.connect(stream).flatMap(new LeftIdentityCoRichFlatMapFunction())
 
-				// -------------- third vertex - the stateful one that also fails ----------------
+				// -------------- third vertex - stateful  ----------------
 				.map(new StringPrefixCountRichMapFunction())
 				.startNewChain()
 				.map(new StatefulCounterFunction())
 
-						// -------------- fourth vertex - reducer and the sink ----------------
+				// -------------- fourth vertex - reducer (failing) and the sink ----------------
 				.groupBy("prefix")
 				.reduce(new OnceFailingReducer(NUM_STRINGS))
 				.addSink(new SinkFunction<PrefixCount>() {
 
 					@Override
-					public void invoke(PrefixCount value) throws Exception {
+					public void invoke(PrefixCount value) {
 						// Do nothing here
 					}
 				});
@@ -123,15 +122,14 @@ public class CoStreamCheckpointingITCase extends StreamFaultToleranceTestBase {
 		}
 
 		if (!StringPrefixCountRichMapFunction.restoreCalledAtLeastOnce) {
-			Assert.fail("Restore was never called on counting Map function.");
+			System.err.println("Test inconclusive: Restore was never called on counting Map function.");
 		}
 
 		if (!LeftIdentityCoRichFlatMapFunction.restoreCalledAtLeastOnce) {
-			Assert.fail("Restore was never called on counting CoMap function.");
+			System.err.println("Test inconclusive: Restore was never called on counting CoMap function.");
 		}
 
 		// verify that we counted exactly right
-
 		assertEquals(NUM_STRINGS, filterSum);
 		assertEquals(NUM_STRINGS, coMapSum);
 		assertEquals(NUM_STRINGS, mapSum);
@@ -301,19 +299,20 @@ public class CoStreamCheckpointingITCase extends StreamFaultToleranceTestBase {
 	}
 
 	private static class StringPrefixCountRichMapFunction extends RichMapFunction<String, PrefixCount> implements Checkpointed<Long> {
-
-		private long count = 0;
+		
 		static final long[] counts = new long[PARALLELISM];
 		static volatile boolean restoreCalledAtLeastOnce = false;
+		
+		private long count;
 
 		@Override
-		public PrefixCount map(String value) throws IOException {
+		public PrefixCount map(String value) {
 			count += 1;
 			return new PrefixCount(value.substring(0, 1), value, 1L);
 		}
 
 		@Override
-		public Long snapshotState(long checkpointId, long checkpointTimestamp) throws Exception {
+		public Long snapshotState(long checkpointId, long checkpointTimestamp) {
 			return count;
 		}
 
@@ -334,25 +333,25 @@ public class CoStreamCheckpointingITCase extends StreamFaultToleranceTestBase {
 
 	private static class LeftIdentityCoRichFlatMapFunction extends RichCoFlatMapFunction<String, String, String> implements Checkpointed<Long> {
 
-		long count = 0;
 		static final long[] counts = new long[PARALLELISM];
-
 		static volatile boolean restoreCalledAtLeastOnce = false;
+		
+		private long count;
 
 		@Override
-		public void flatMap1(String value, Collector<String> out) throws IOException {
+		public void flatMap1(String value, Collector<String> out) {
 			count += 1;
 
 			out.collect(value);
 		}
 
 		@Override
-		public void flatMap2(String value, Collector<String> out) throws IOException {
+		public void flatMap2(String value, Collector<String> out) {
 			// we ignore the values from the second input
 		}
 
 		@Override
-		public Long snapshotState(long checkpointId, long checkpointTimestamp) throws Exception {
+		public Long snapshotState(long checkpointId, long checkpointTimestamp) {
 			return count;
 		}