feat(verifier): Throw more specific exception when verification fails

Resolves pact-foundation#505

Author: adamrodger

Diff for: src/PactNet.Abstractions/Exceptions/PactVerificationFailedException.cs

@@ -0,0 +1,36 @@
+using System;
+
+namespace PactNet.Exceptions
+{
+    /// <summary>
+    /// Pact verification failed
+    /// </summary>
+    [Serializable]
+    public class PactVerificationFailedException : PactFailureException
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PactVerificationFailedException" /> class
+        /// </summary>
+        public PactVerificationFailedException()
+            : this("The pact failed verification")
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PactVerificationFailedException" /> class
+        /// </summary>
+        /// <param name="message">The message that describes the error</param>
+        public PactVerificationFailedException(string message) : base(message)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PactVerificationFailedException" /> class
+        /// </summary>
+        /// <param name="message">The error message that explains the reason for the exception</param>
+        /// <param name="innerException">The exception that is the cause of the current exception, or a null reference (Nothing in Visual Basic) if no inner exception is specified</param>
+        public PactVerificationFailedException(string message, Exception innerException) : base(message, innerException)
+        {
+        }
+    }
+}

Diff for: src/PactNet/Verifier/InteropVerifierProvider.cs

@@ -235,7 +235,7 @@ public void Execute()
 
             string error = result switch
             {
-                1 => "Pact verification failed",
+                1 => throw new PactVerificationFailedException("Pact verification failed"),
                 2 => "Failed to run the verification",
                 _ => $"An unknown error occurred: {result}"
             };

Diff for: tests/PactNet.Tests/Verifier/InteropVerifierProviderTests.cs

@@ -53,7 +53,7 @@ public void HappyPathIntegrationTest()
 
             Action action = () => provider.Execute();
 
-            action.Should().Throw<PactFailureException>();
+            action.Should().Throw<PactVerificationFailedException>();
         }
 
         [Fact]
@@ -73,7 +73,7 @@ public void SetPublishOptions_NoBuildUri_IsValid()
 
             Action action = () => provider.Execute();
 
-            action.Should().Throw<PactFailureException>();
+            action.Should().Throw<PactVerificationFailedException>();
         }
     }
 }