[SpecsUtils] commiting MultiConsumerTest class

(this file was uncommited on my machine for a long time; i think it was
just a test for something related to the BTF)

SpecsUtils/test/pt/up/fe/specs/util/threadstream/MultiConsumerTest.java

@@ -0,0 +1,102 @@
+package pt.up.fe.specs.util.threadstream;
+
+import java.util.ArrayList;
+import java.util.Random;
+
+import org.junit.Test;
+
+import pt.up.fe.specs.util.collections.concurrentchannel.ChannelConsumer;
+
+public class MultiConsumerTest {
+
+    /*
+     * Test producer
+     */
+    private class StringProducer implements ObjectProducer<String> {
+
+        private int producecount;
+
+        public StringProducer(int producecount) {
+            this.producecount = producecount;
+        }
+
+        @Override
+        public String getPoison() {
+            return "kill";
+        }
+
+        public String getString() {
+
+            if (this.producecount-- == 0)
+                return null;
+
+            int leftLimit = 97; // letter 'a'
+            int rightLimit = 122; // letter 'z'
+            int targetStringLength = 10;
+            Random random = new Random();
+
+            return random.ints(leftLimit, rightLimit + 1)
+                    .limit(targetStringLength)
+                    .collect(StringBuilder::new, StringBuilder::appendCodePoint, StringBuilder::append)
+                    .toString();
+        }
+
+        @Override
+        public void close() throws Exception {
+            // TODO Auto-generated method stub
+        }
+    }
+
+    /*
+     * Test custom stream name
+     */
+    private class StringStream extends GenericObjectStream<String> {
+
+        public StringStream(StringProducer producer, ChannelConsumer<String> consumer) {
+            super(consumer, producer.getPoison());
+        }
+    }
+
+    /*
+     * Test consumer
+     */
+    private class StringConsumer {
+
+        public StringConsumer() {
+            // TODO Auto-generated constructor stub
+        }
+
+        public Integer consumeString(StringStream istream) {
+
+            Integer hashcode = 0;
+            String str = null;
+            while ((str = istream.next()) != null) {
+                hashcode += str.hashCode();
+            }
+            return hashcode;
+        }
+
+    }
+
+    @Test
+    public void test() {
+
+        // host for threads
+        var sb = new StringProducer(100000);
+        var streamengine = new ProducerEngine<String, StringProducer>(sb, op -> op.getString(),
+                cc -> new StringStream(sb, cc));
+
+        // new consumer thread via lambda
+        var threadlist = new ArrayList<ConsumerThread<String, ?>>();
+        for (int i = 0; i < 20; i++)
+            threadlist.add(streamengine.subscribe(os -> (new StringConsumer()).consumeString((StringStream) os)));
+
+        // launch all threads (blocking)
+        streamengine.launch();
+
+        // consume
+        for (int i = 0; i < 20; i++) {
+            System.out.println(threadlist.get(i).getConsumeResult());
+        }
+    }
+}