Added the ClearAllDimensions and a test to check it

Author: EgressGlynn

libraries/src/AWS.Lambda.Powertools.Metrics/IMetrics.cs

@@ -96,4 +96,9 @@ void PushSingleMetric(string metricName, double value, MetricUnit unit, string n
     /// </summary>
     /// <param name="metricsOverflow">if set to <c>true</c> [metrics overflow].</param>
     void Flush(bool metricsOverflow = false);
+    
+    /// <summary>
+    ///     Clears both default dimensions and dimensions lists
+    /// </summary>
+    void ClearAllDimensions();
 }

libraries/src/AWS.Lambda.Powertools.Metrics/Metrics.cs

@@ -212,6 +212,14 @@ void IMetrics.Flush(bool metricsOverflow)
                     "##WARNING## Metrics and Metadata have not been specified. No data will be sent to Cloudwatch Metrics.");
         }
     }
+    
+    /// <summary>
+    ///     Clears all Dimensions in both DefaultDimensions and Dimensions
+    /// </summary>
+    void IMetrics.ClearAllDimensions()
+    {
+        _context.ClearAllDimensions();
+    }
 
     /// <summary>
     ///     Serialize global context object
@@ -317,6 +325,14 @@ public static void SetDefaultDimensions(Dictionary<string, string> defaultDimens
     {
         _instance.SetDefaultDimensions(defaultDimensions);
     }
+    
+    /// <summary>
+    ///     Clears both default dimensions and dimensions lists
+    /// </summary>
+    public static void ClearAllDimensions()
+    {
+        _instance.ClearAllDimensions();
+    }
 
     /// <summary>
     ///     Flushes metrics in Embedded Metric Format (EMF) to Standard Output. In Lambda, this output is collected

libraries/src/AWS.Lambda.Powertools.Metrics/Model/Metadata.cs

@@ -175,4 +175,12 @@ internal Dictionary<string, string> ExpandAllDimensionSets()
 
         return dimensionSets;
     }
+
+    /// <summary>
+    ///     Clears both default dimensions and dimensions lists
+    /// </summary>
+    internal void ClearAllDimensions()
+    {
+        _metricDirective.ClearAllDimensions();
+    }
 }

libraries/src/AWS.Lambda.Powertools.Metrics/Model/MetricDirective.cs

@@ -199,10 +199,12 @@ internal void AddDimension(DimensionSet dimension)
     /// <param name="defaultDimensions">Default dimensions list</param>
     internal void SetDefaultDimensions(List<DimensionSet> defaultDimensions)
     {
-        if (!defaultDimensions.Any())
-            return;
-
-        DefaultDimensions = defaultDimensions;
+        if (!DefaultDimensions.Any())
+            DefaultDimensions = defaultDimensions;
+        else
+            foreach (var item in defaultDimensions)
+                if (!DefaultDimensions.Any(d => d.DimensionKeys.Contains(item.DimensionKeys[0])))
+                    DefaultDimensions.Add(item);
     }
 
     /// <summary>
@@ -223,4 +225,13 @@ internal Dictionary<string, string> ExpandAllDimensionSets()
 
         return dimensions;
     }
+
+    /// <summary>
+    ///     Clears both default dimensions and dimensions lists
+    /// </summary>
+    internal void ClearAllDimensions()
+    {
+        Dimensions.Clear();
+        DefaultDimensions.Clear();
+    }
 }

libraries/src/AWS.Lambda.Powertools.Metrics/Model/MetricsContext.cs

@@ -162,4 +162,12 @@ public string Serialize()
     {
         return _rootNode.Serialize();
     }
+    
+    /// <summary>
+    ///     Clears both default dimensions and dimensions lists
+    /// </summary>
+    public void ClearAllDimensions()
+    {
+        _rootNode.AWS.ClearAllDimensions();
+    }
 }

libraries/tests/AWS.Lambda.Powertools.Metrics.Tests/ClearDimensionsTests.cs

@@ -0,0 +1,51 @@
+using System;
+using System.IO;
+using AWS.Lambda.Powertools.Common;
+using Moq;
+using Xunit;
+
+namespace AWS.Lambda.Powertools.Metrics.Tests;
+
+[Collection("Sequential")]
+public class ClearDimensionsTests
+{
+    [Fact]
+    public void WhenClearAllDimensions_NoDimensionsInOutput()
+    {
+        // Arrange
+        var methodName = Guid.NewGuid().ToString();
+        var consoleOut = new StringWriter();
+        Console.SetOut(consoleOut);
+
+        var configurations = new Mock<IPowertoolsConfigurations>();
+
+        var logger = new Metrics(
+            configurations.Object,
+            nameSpace: "dotnet-powertools-test",
+            service: "testService"
+        );
+
+        var handler = new MetricsAspectHandler(
+            logger,
+            false
+        );
+
+        var eventArgs = new AspectEventArgs { Name = methodName };
+
+        // Act
+        handler.OnEntry(eventArgs);
+
+        Metrics.ClearAllDimensions();
+        Metrics.AddMetric($"Metric Name", 1, MetricUnit.Count);
+
+        handler.OnExit(eventArgs);
+
+        var metricsOutput = consoleOut.ToString();
+
+        // Assert
+        Assert.Contains("{\"Namespace\":\"dotnet-powertools-test\",\"Metrics\":[{\"Name\":\"Metric Name\",\"Unit\":\"Count\"}],\"Dimensions\":[[]]", metricsOutput);
+
+        // Reset
+        handler.ResetForTest();
+    }
+}