Reject maxBatchSize and flushPeriodMilliseconds below 1 and negative retries

BetterStack.Logs.NLog/BetterStackLogsTarget.cs

@@ -113,6 +113,16 @@ protected override void InitializeTarget()
             if (!Uri.TryCreate(endpointUrl, UriKind.Absolute, out _)) {
                 throw new NLogConfigurationException($"BetterStack.Logs: endpoint is \"{endpoint}\". Set it to the ingesting host of your Better Stack source.");
             }
+            // 0 would leave the drain spinning on a core: without taking any logs, or without waiting between flushes
+            if (MaxBatchSize < 1) {
+                throw new NLogConfigurationException($"BetterStack.Logs: maxBatchSize is {MaxBatchSize}. Set it to 1 or more.");
+            }
+            if (FlushPeriodMilliseconds < 1) {
+                throw new NLogConfigurationException($"BetterStack.Logs: flushPeriodMilliseconds is {FlushPeriodMilliseconds}. Set it to 1 or more.");
+            }
+            if (Retries < 0) {
+                throw new NLogConfigurationException($"BetterStack.Logs: retries is {Retries}. Set it to 0 or more.");
+            }
 
             var client = new Client(
                 sourceToken,

tests/BetterStack.Logs.NLog.Tests/BetterStackLogsTargetTests.cs

@@ -134,8 +134,8 @@
                 LoggerFor(target).Info("Hello");
 
                 var connection = server.AcceptTcpClientAsync();
                 Assert.True(connection.Wait(TimeSpan.FromSeconds(30)), "No connection arrived within 30 seconds.");
                 using (var client = connection.Result) {
                     client.ReceiveTimeout = 30000;
                     // A TLS handshake record starts with 0x16, a plain http request with "POST"
                     Assert.Equal(0x16, client.GetStream().ReadByte());
@@ -480,5 +480,48 @@
             Assert.Equal("Tracing the code!", (string)log["message"]);
             Assert.Equal("Trace", (string)log["level"]);
         }
+
+        [Fact]
+        public void ReportsMaxBatchSizeBelowOneAsConfigurationError()
+        {
+            logFactory.ThrowConfigExceptions = true;
+            var target = Target();
+            target.MaxBatchSize = 0;
+
+            var exception = Assert.Throws<NLogConfigurationException>(() => LoggerFor(target));
+            Assert.Equal("BetterStack.Logs: maxBatchSize is 0. Set it to 1 or more.", exception.Message);
+        }
+
+        [Fact]
+        public void ReportsFlushPeriodBelowOneMillisecondAsConfigurationError()
+        {
+            logFactory.ThrowConfigExceptions = true;
+            var target = Target();
+            target.FlushPeriodMilliseconds = 0;
+
+            var exception = Assert.Throws<NLogConfigurationException>(() => LoggerFor(target));
+            Assert.Equal("BetterStack.Logs: flushPeriodMilliseconds is 0. Set it to 1 or more.", exception.Message);
+        }
+
+        [Fact]
+        public void ReportsNegativeRetriesAsConfigurationError()
+        {
+            logFactory.ThrowConfigExceptions = true;
+            var target = Target();
+            target.Retries = -1;
+
+            var exception = Assert.Throws<NLogConfigurationException>(() => LoggerFor(target));
+            Assert.Equal("BetterStack.Logs: retries is -1. Set it to 0 or more.", exception.Message);
+        }
+
+        [Fact]
+        public void AcceptsZeroRetries()
+        {
+            logFactory.ThrowConfigExceptions = true;
+            var target = Target();
+            target.Retries = 0;
+
+            Assert.Null(Record.Exception(() => LoggerFor(target)));
+        }
     }
 }