Make WireMockAssertions extendable (#1082)

test/WireMock.Net.Tests/FluentAssertions/WireMockAssertionsExtensions.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Linq;
+using FluentAssertions;
+using FluentAssertions.Execution;
+
+// ReSharper disable once CheckNamespace
+namespace WireMock.FluentAssertions;
+
+public static class WireMockAssertionsExtensions
+{
+    [CustomAssertion]
+    public static AndWhichConstraint<WireMockAssertions, string> AtAbsoluteUrl2(this WireMockAssertions assertions,
+        string absoluteUrl, string because = "", params object[] becauseArgs)
+    {
+        var (filter, condition) = assertions.BuildFilterAndCondition(request => string.Equals(request.AbsoluteUrl, absoluteUrl, StringComparison.OrdinalIgnoreCase));
+
+        Execute.Assertion
+            .BecauseOf(because, becauseArgs)
+            .Given(() => assertions.RequestMessages)
+            .ForCondition(requests => assertions.CallsCount == 0 || requests.Any())
+            .FailWith(
+                "Expected {context:wiremockserver} to have been called at address matching the absolute url {0}{reason}, but no calls were made.",
+                absoluteUrl
+            )
+            .Then
+            .ForCondition(condition)
+            .FailWith(
+                "Expected {context:wiremockserver} to have been called at address matching the absolute url {0}{reason}, but didn't find it among the calls to {1}.",
+                _ => absoluteUrl,
+                requests => requests.Select(request => request.AbsoluteUrl)
+            );
+
+        assertions.FilterRequestMessages(filter);
+
+        return new AndWhichConstraint<WireMockAssertions, string>(assertions, absoluteUrl);
+    }
+}