diff --git a/test/OpenIddict.Tests/OpenIddictProviderTests.Authentication.cs b/test/OpenIddict.Tests/OpenIddictProviderTests.Authentication.cs
index 567767c8..30e8e548 100644
--- a/test/OpenIddict.Tests/OpenIddictProviderTests.Authentication.cs
+++ b/test/OpenIddict.Tests/OpenIddictProviderTests.Authentication.cs
@@ -515,7 +515,7 @@ namespace OpenIddict.Tests
             var identifier = (string) response[OpenIdConnectConstants.Parameters.RequestId];
 
             // Assert
-            Assert.Equal(1, response.GetParameters().Count());
+            Assert.Single(response.GetParameters());
             Assert.NotNull(identifier);
 
             cache.Verify(mock => mock.SetAsync(
diff --git a/test/OpenIddict.Tests/OpenIddictProviderTests.Discovery.cs b/test/OpenIddict.Tests/OpenIddictProviderTests.Discovery.cs
index e354324f..79740b26 100644
--- a/test/OpenIddict.Tests/OpenIddictProviderTests.Discovery.cs
+++ b/test/OpenIddict.Tests/OpenIddictProviderTests.Discovery.cs
@@ -56,7 +56,7 @@ namespace OpenIddict.Tests
             var types = ((JArray) response[OpenIdConnectConstants.Metadata.GrantTypesSupported]).Values<string>();
 
             // Assert
-            Assert.Equal(1, types.Count());
+            Assert.Single(types);
             Assert.Contains(flow, types);
         }
 
diff --git a/test/OpenIddict.Tests/OpenIddictProviderTests.Introspection.cs b/test/OpenIddict.Tests/OpenIddictProviderTests.Introspection.cs
index 2577952c..75d15783 100644
--- a/test/OpenIddict.Tests/OpenIddictProviderTests.Introspection.cs
+++ b/test/OpenIddict.Tests/OpenIddictProviderTests.Introspection.cs
@@ -224,7 +224,7 @@ namespace OpenIddict.Tests
             });
 
             // Assert
-            Assert.Equal(1, response.GetParameters().Count());
+            Assert.Single(response.GetParameters());
             Assert.False((bool) response[OpenIdConnectConstants.Claims.Active]);
         }
 
@@ -398,7 +398,7 @@ namespace OpenIddict.Tests
             });
 
             // Assert
-            Assert.Equal(1, response.GetParameters().Count());
+            Assert.Single(response.GetParameters());
             Assert.False((bool) response[OpenIdConnectConstants.Claims.Active]);
 
             Mock.Get(manager).Verify(mock => mock.FindByIdAsync("3E228451-1555-46F7-A471-951EFBA23A56", It.IsAny<CancellationToken>()), Times.Once());
@@ -462,7 +462,7 @@ namespace OpenIddict.Tests
             });
 
             // Assert
-            Assert.Equal(1, response.GetParameters().Count());
+            Assert.Single(response.GetParameters());
             Assert.False((bool) response[OpenIdConnectConstants.Claims.Active]);
 
             Mock.Get(manager).Verify(mock => mock.FindByIdAsync("3E228451-1555-46F7-A471-951EFBA23A56", It.IsAny<CancellationToken>()), Times.Once());
diff --git a/test/OpenIddict.Tests/OpenIddictProviderTests.Revocation.cs b/test/OpenIddict.Tests/OpenIddictProviderTests.Revocation.cs
index 740141ce..557bdacb 100644
--- a/test/OpenIddict.Tests/OpenIddictProviderTests.Revocation.cs
+++ b/test/OpenIddict.Tests/OpenIddictProviderTests.Revocation.cs
@@ -336,7 +336,7 @@ namespace OpenIddict.Tests
             });
 
             // Assert
-            Assert.Equal(0, response.GetParameters().Count());
+            Assert.Empty(response.GetParameters());
 
             Mock.Get(manager).Verify(mock => mock.FindByIdAsync("3E228451-1555-46F7-A471-951EFBA23A56", It.IsAny<CancellationToken>()), Times.Once());
             Mock.Get(manager).Verify(mock => mock.RevokeAsync(It.IsAny<OpenIddictToken>(), It.IsAny<CancellationToken>()), Times.Never());
@@ -382,7 +382,7 @@ namespace OpenIddict.Tests
             });
 
             // Assert
-            Assert.Equal(0, response.GetParameters().Count());
+            Assert.Empty(response.GetParameters());
 
             Mock.Get(manager).Verify(mock => mock.FindByIdAsync("3E228451-1555-46F7-A471-951EFBA23A56", It.IsAny<CancellationToken>()), Times.Once());
             Mock.Get(manager).Verify(mock => mock.RevokeAsync(token, It.IsAny<CancellationToken>()), Times.Once());
diff --git a/test/OpenIddict.Tests/OpenIddictProviderTests.Session.cs b/test/OpenIddict.Tests/OpenIddictProviderTests.Session.cs
index aa272c0b..2e692099 100644
--- a/test/OpenIddict.Tests/OpenIddictProviderTests.Session.cs
+++ b/test/OpenIddict.Tests/OpenIddictProviderTests.Session.cs
@@ -120,7 +120,7 @@ namespace OpenIddict.Tests
             var identifier = (string) response[OpenIdConnectConstants.Parameters.RequestId];
 
             // Assert
-            Assert.Equal(1, response.GetParameters().Count());
+            Assert.Single(response.GetParameters());
             Assert.NotNull(identifier);
 
             cache.Verify(mock => mock.SetAsync(