fix: avoid null exception when received body is empty but recorded body isn't

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - Add .NET 8.0 support
 - `AdvancedSettings` uses `MatchRules.Default` instead of a new instance of `MatchRules` if not provided during construction
+- Fix `NullReferenceException` when trying to match by body with a null body (`refit` compatibility)
 
 ## v0.9.0 (2023-05-17)
 

EasyVCR.Tests/ClientTest.cs

@@ -513,6 +513,26 @@ public async Task TestMatchNonJsonBody()
  Assert.IsNotNull(response);
  }
 
+ [TestMethod]
+ public async Task TestMatchEmptyStringBodyToNonEmptyStringBody()
+ {
+ var cassette = TestUtils.GetCassette("test_match_empty_body");
+ cassette.Erase(); // Erase cassette before recording
+
+ const string url = "https://httpbin.org/post";
+
+ var client = HttpClients.NewHttpClient(cassette, Mode.Record);
+ var someContent = new ByteArrayContent(Encoding.UTF8.GetBytes("non_empty_string_body"));
+ _ = await client.PostAsync(url, someContent);
+
+ // try to replay the request with match by body enforcement
+ client = HttpClients.NewHttpClient(cassette, Mode.Replay, new AdvancedSettings
+ {
+ MatchRules = new MatchRules().ByBody()
+ });
+ var emptyContent = new ByteArrayContent(Encoding.UTF8.GetBytes(string.Empty));
+ await Assert.ThrowsExceptionAsync<VCRException>(async () => await client.PostAsync(url, emptyContent), $"No interaction found for request POST {url}");
+ }
 
  [TestMethod]
  public async Task TestInteractionElements()

EasyVCR/InternalUtilities/Extensions.cs

@@ -0,0 +1,7 @@
+namespace EasyVCR.InternalUtilities
+{
+ public static class Extensions
+ {
+ public static bool IsEmptyStringOrNull(this string? str) => str == null || string.IsNullOrWhiteSpace(str);
+ }
+}

EasyVCR/MatchRules.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Web;
+using EasyVCR.InternalUtilities;
 using EasyVCR.RequestElements;
 using JsonSerialization = EasyVCR.InternalUtilities.JSON.Serialization;
 using XmlSerialization = EasyVCR.InternalUtilities.XML.Serialization;
@@ -132,7 +133,7 @@ public MatchRules ByBody(List<CensorElement>? ignoredElements = null)
  return true;
 
  if (received.Body == null || recorded.Body == null)
- // one has a null body, so they don't match
+ // one has a null body, the other does not, so they don't match
  return false;
 
  var receivedBody = received.Body;
@@ -155,11 +156,24 @@ public MatchRules ByBody(List<CensorElement>? ignoredElements = null)
  // not JSON, using the string as it is
  }
 
+ if (receivedBody.IsEmptyStringOrNull())
+ // short-cut if the received body is empty
+ receivedBody = null;
+
+ if (recordedBody.IsEmptyStringOrNull())
+ // short-cut if the recorded body is empty
+ recordedBody = null;
+
  if (receivedBody == null && recordedBody == null)
  // both have empty string bodies, so they match
  return true;
 
- return receivedBody!.Equals(recordedBody, StringComparison.OrdinalIgnoreCase);
+ if (receivedBody == null || recordedBody == null)
+ // one has a null body, the other does not, so they don't match
+ return false;
+
+ // if the bodies are not null, then we can compare them
+ return receivedBody.Equals(recordedBody, StringComparison.OrdinalIgnoreCase);
  });
  return this;
  }