Fix unbuffered batch metrics send

src/JustEat.StatsD.Tests/StringBasedStatsDPublisherTests.cs

@@ -0,0 +1,89 @@
+using System;
+using Moq;
+using Xunit;
+
+namespace JustEat.StatsD
+{
+    public static class StringBasedStatsDPublisherTests
+    {
+        [Fact]
+        public static void Decrement_Sends_Multiple_Metrics()
+        {
+            // Arrange
+            var mock = new Mock<IStatsDTransport>();
+
+            var config = new StatsDConfiguration
+            {
+                Prefix = "red",
+            };
+
+            var publisher = new StringBasedStatsDPublisher(config, mock.Object);
+
+            // Act
+            publisher.Decrement(10, 1, "white", "blue");
+
+            // Assert
+            mock.Verify((p) => p.Send("red.white:-10|c"), Times.Once());
+            mock.Verify((p) => p.Send("red.blue:-10|c"), Times.Once());
+        }
+
+        [Fact]
+        public static void Increment_Sends_Multiple_Metrics()
+        {
+            // Arrange
+            var mock = new Mock<IStatsDTransport>();
+
+            var config = new StatsDConfiguration
+            {
+                Prefix = "red",
+            };
+
+            var publisher = new StringBasedStatsDPublisher(config, mock.Object);
+
+            // Act
+            publisher.Increment(10, 1, "white", "blue");
+
+            // Assert
+            mock.Verify((p) => p.Send("red.white:10|c"), Times.Once());
+            mock.Verify((p) => p.Send("red.blue:10|c"), Times.Once());
+        }
+
+        [Fact]
+        public static void Metrics_Not_Sent_If_Array_Is_Null_Or_Empty()
+        {
+            // Arrange
+            var mock = new Mock<IStatsDTransport>();
+            var config = new StatsDConfiguration();
+
+            var publisher = new StringBasedStatsDPublisher(config, mock.Object);
+
+            // Act
+            publisher.Decrement(1, 1, null as string[]);
+            publisher.Increment(1, 1, null as string[]);
+            publisher.Decrement(1, 1, Array.Empty<string>());
+            publisher.Increment(1, 1, Array.Empty<string>());
+            publisher.Decrement(1, 1, new[] { string.Empty });
+            publisher.Increment(1, 1, new[] { string.Empty });
+
+            // Assert
+            mock.Verify((p) => p.Send(It.IsAny<string>()), Times.Never());
+        }
+
+        [Fact]
+        public static void Metrics_Not_Sent_If_No_Metrics()
+        {
+            // Arrange
+            var mock = new Mock<IStatsDTransport>();
+            var config = new StatsDConfiguration();
+
+            var publisher = new StringBasedStatsDPublisher(config, mock.Object);
+
+            // Act
+            publisher.Decrement(1, 0, new[] { "foo" });
+            publisher.Increment(1, 0, new[] { "bar" });
+
+            // Assert
+            mock.Verify((p) => p.Send(It.IsAny<string>()), Times.Never());
+        }
+    }
+}

src/JustEat.StatsD/StatsDMessageFormatter.cs

@@ -16,15 +16,17 @@ public class StatsDMessageFormatter
         private readonly string _prefix;
 
         public StatsDMessageFormatter()
-            : this(string.Empty) {}
+            : this(string.Empty)
+        {
+        }
 
-            public StatsDMessageFormatter(string prefix)
+        public StatsDMessageFormatter(string prefix)
         {
             _prefix = prefix;
 
             if (!string.IsNullOrWhiteSpace(_prefix))
             {
-                _prefix = _prefix + "."; // if we have something, then append a . to it to make concatenations easy.
+                _prefix = _prefix + "."; // If we have something, then append a '.' to it to make concatenations easy.
             }
         }
 
@@ -51,7 +53,6 @@ public string Decrement(long magnitude, string statBucket)
             return Decrement(magnitude, DefaultSampleRate, statBucket);
         }
 
-
         public string Decrement(long magnitude, double sampleRate, string statBucket)
         {
             magnitude = magnitude < 0 ? magnitude : -magnitude;

src/JustEat.StatsD/StringBasedStatsDPublisher.cs

@@ -59,7 +59,18 @@ public void Increment(long value, double sampleRate, string bucket)
 
         public void Increment(long value, double sampleRate, params string[] buckets)
         {
-            Send(_formatter.Increment(value, sampleRate, buckets));
+            if (buckets == null || buckets.Length == 0)
+            {
+                return;
+            }
+
+            foreach (string bucket in buckets)
+            {
+                if (!string.IsNullOrEmpty(bucket))
+                {
+                    Send(_formatter.Increment(value, sampleRate, bucket));
+                }
+            }
         }
 
         public void Decrement(string bucket)
@@ -79,7 +90,18 @@ public void Decrement(long value, double sampleRate, string bucket)
 
         public void Decrement(long value, double sampleRate, params string[] buckets)
         {
-            Send(_formatter.Decrement(value, sampleRate, buckets));
+            if (buckets == null || buckets.Length == 0)
+            {
+                return;
+            }
+
+            foreach (string bucket in buckets)
+            {
+                if (!string.IsNullOrEmpty(bucket))
+                {
+                    Send(_formatter.Decrement(value, sampleRate, bucket));
+                }
+            }
         }
 
         public void Gauge(double  value, string bucket)
@@ -119,6 +141,11 @@ public void MarkEvent(string name)
 
         private void Send(string metric)
         {
+            if (metric.Length == 0)
+            {
+                return;
+            }
+
             try
             {
                 _transport.Send(metric);