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Merged
Youssef1313 merged 10 commits into from
Apr 17, 2026
Merged

Improve IsExactInstanceOfType error message for NULL values #7418

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90a7b1f
Initial plan
Copilot Feb 16, 2026
821796a
Add NULL detection to IsExactInstanceOfType error message and update …
Copilot Feb 16, 2026
076ac24
Remove accidentally committed backup files
Copilot Feb 16, 2026
93c6664
Add proper punctuation before NULL message when userMessage doesn't e…
Copilot Feb 16, 2026
9748596
Use trimmed message consistently when adding NULL indicator
Copilot Feb 16, 2026
8307e33
Improve punctuation handling - handle empty messages and use index ac…
Copilot Feb 16, 2026
0b7ef63
Merge branch 'main' into copilot/improve-isexactinstanceoftype-error-…
Evangelink Apr 14, 2026
7cdefb8
Address review comments: fix null safety, simplify logic, add edge ca…
Copilot Apr 14, 2026
9c081eb
Address review comments
Evangelink Apr 16, 2026
459d31d
Address PR feedback: reuse standard fail message for null values and …
Evangelink Apr 17, 2026
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10 changes: 4 additions & 6 deletions src/TestFramework/TestFramework/Assertions/Assert.IsExactInstanceOfType.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -331,16 +331,14 @@ private static bool IsExactInstanceOfTypeFailing([NotNullWhen(false)] object? va
[DoesNotReturn]
private static void ThrowAssertIsExactInstanceOfTypeFailed(object? value, Type? expectedType, string userMessage)
{
string finalMessage = userMessage;
if (expectedType is not null && value is not null)
{
finalMessage = string.Format(
string finalMessage = expectedType is not null
? string.Format(
CultureInfo.CurrentCulture,
FrameworkMessages.IsExactInstanceOfFailMsg,
userMessage,
expectedType.ToString(),
value.GetType().ToString());
}
value?.GetType().ToString() ?? "null")
: userMessage;
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Evangelink marked this conversation as resolved.

ThrowAssertFailed("Assert.IsExactInstanceOfType", finalMessage);
}
Expand Down
10 changes: 4 additions & 6 deletions src/TestFramework/TestFramework/Assertions/Assert.IsInstanceOfType.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -333,16 +333,14 @@ private static bool IsInstanceOfTypeFailing([NotNullWhen(false)] object? value,
[DoesNotReturn]
private static void ThrowAssertIsInstanceOfTypeFailed(object? value, Type? expectedType, string userMessage)
{
string finalMessage = userMessage;
if (expectedType is not null && value is not null)
{
finalMessage = string.Format(
string finalMessage = expectedType is not null
? string.Format(
CultureInfo.CurrentCulture,
FrameworkMessages.IsInstanceOfFailMsg,
userMessage,
expectedType.ToString(),
value.GetType().ToString());
}
value?.GetType().ToString() ?? "null")
: userMessage;
Comment thread
Evangelink marked this conversation as resolved.

ThrowAssertFailed("Assert.IsInstanceOfType", finalMessage);
}
Expand Down
8 changes: 4 additions & 4 deletions test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.IsExactInstanceOfTypeTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ public void ExactInstanceOfTypeShouldFailWhenValueIsNull()
{
Action action = () => Assert.IsExactInstanceOfType(null, typeof(AssertTests));
action.Should().Throw<AssertFailedException>()
.WithMessage("Assert.IsExactInstanceOfType failed. 'value' expression: 'null'.");
.WithMessage("Assert.IsExactInstanceOfType failed. 'value' expression: 'null'. Expected exact type:<Microsoft.VisualStudio.TestPlatform.TestFramework.UnitTests.AssertTests>. Actual type:<null>.");
}

public void ExactInstanceOfTypeShouldFailWhenTypeIsNull()
Expand Down Expand Up @@ -56,7 +56,7 @@ public void ExactInstanceOfType_WithStringMessage_ShouldFailWhenValueIsNull()
{
Action action = () => Assert.IsExactInstanceOfType(null, typeof(AssertTests), "User-provided message");
action.Should().Throw<AssertFailedException>()
.WithMessage("Assert.IsExactInstanceOfType failed. 'value' expression: 'null'. User-provided message");
.WithMessage("Assert.IsExactInstanceOfType failed. 'value' expression: 'null'. User-provided message Expected exact type:<Microsoft.VisualStudio.TestPlatform.TestFramework.UnitTests.AssertTests>. Actual type:<null>.");
}

public void ExactInstanceOfType_WithStringMessage_ShouldFailWhenTypeIsNull()
Expand All @@ -82,7 +82,7 @@ public async Task ExactInstanceOfType_WithInterpolatedString_ShouldFailWhenValue
DateTime dateTime = DateTime.Now;
Func<Task> action = async () => Assert.IsExactInstanceOfType(null, typeof(AssertTests), $"User-provided message. {o}, {o,35}, {await GetHelloStringAsync()}, {new DummyIFormattable()}, {dateTime:tt}, {dateTime,5:tt}");
(await action.Should().ThrowAsync<AssertFailedException>())
.WithMessage($"Assert.IsExactInstanceOfType failed. 'value' expression: 'null'. User-provided message. DummyClassTrackingToStringCalls, DummyClassTrackingToStringCalls, Hello, DummyIFormattable.ToString(), {string.Format(null, "{0:tt}", dateTime)}, {string.Format(null, "{0,5:tt}", dateTime)}");
.WithMessage($"Assert.IsExactInstanceOfType failed. 'value' expression: 'null'. User-provided message. DummyClassTrackingToStringCalls, DummyClassTrackingToStringCalls, Hello, DummyIFormattable.ToString(), {string.Format(null, "{0:tt}", dateTime)}, {string.Format(null, "{0,5:tt}", dateTime)} Expected exact type:<Microsoft.VisualStudio.TestPlatform.TestFramework.UnitTests.AssertTests>. Actual type:<null>.");
o.WasToStringCalled.Should().BeTrue();
}

Expand Down Expand Up @@ -141,7 +141,7 @@ public void IsExactInstanceOfTypeUsingGenericType_WhenValueIsNull_Fails()
{
Action action = () => Assert.IsExactInstanceOfType<AssertTests>(null);
action.Should().Throw<AssertFailedException>()
.WithMessage("Assert.IsExactInstanceOfType failed. 'value' expression: 'null'.");
.WithMessage("Assert.IsExactInstanceOfType failed. 'value' expression: 'null'. Expected exact type:<Microsoft.VisualStudio.TestPlatform.TestFramework.UnitTests.AssertTests>. Actual type:<null>.");
}

public void IsExactInstanceOfTypeUsingGenericType_WhenTypeMismatch_Fails()
Expand Down
8 changes: 4 additions & 4 deletions test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.IsInstanceOfTypeTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ public void InstanceOfTypeShouldFailWhenValueIsNull()
{
Action action = () => Assert.IsInstanceOfType(null, typeof(AssertTests));
action.Should().Throw<AssertFailedException>()
.WithMessage("Assert.IsInstanceOfType failed. 'value' expression: 'null'.");
.WithMessage("Assert.IsInstanceOfType failed. 'value' expression: 'null'. Expected type:<Microsoft.VisualStudio.TestPlatform.TestFramework.UnitTests.AssertTests>. Actual type:<null>.");
}

public void InstanceOfTypeShouldFailWhenTypeIsNull()
Expand All @@ -37,7 +37,7 @@ public void InstanceOfType_WithStringMessage_ShouldFailWhenValueIsNull()
{
Action action = () => Assert.IsInstanceOfType(null, typeof(AssertTests), "User-provided message");
action.Should().Throw<AssertFailedException>()
.WithMessage("Assert.IsInstanceOfType failed. 'value' expression: 'null'. User-provided message");
.WithMessage("Assert.IsInstanceOfType failed. 'value' expression: 'null'. User-provided message Expected type:<Microsoft.VisualStudio.TestPlatform.TestFramework.UnitTests.AssertTests>. Actual type:<null>.");
}

public void InstanceOfType_WithStringMessage_ShouldFailWhenTypeIsNull()
Expand All @@ -63,7 +63,7 @@ public async Task InstanceOfType_WithInterpolatedString_ShouldFailWhenValueIsNul
DateTime dateTime = DateTime.Now;
Func<Task> action = async () => Assert.IsInstanceOfType(null, typeof(AssertTests), $"User-provided message. {o}, {o,35}, {await GetHelloStringAsync()}, {new DummyIFormattable()}, {dateTime:tt}, {dateTime,5:tt}");
(await action.Should().ThrowAsync<AssertFailedException>())
.WithMessage($"Assert.IsInstanceOfType failed. 'value' expression: 'null'. User-provided message. DummyClassTrackingToStringCalls, DummyClassTrackingToStringCalls, Hello, DummyIFormattable.ToString(), {string.Format(null, "{0:tt}", dateTime)}, {string.Format(null, "{0,5:tt}", dateTime)}");
.WithMessage($"Assert.IsInstanceOfType failed. 'value' expression: 'null'. User-provided message. DummyClassTrackingToStringCalls, DummyClassTrackingToStringCalls, Hello, DummyIFormattable.ToString(), {string.Format(null, "{0:tt}", dateTime)}, {string.Format(null, "{0,5:tt}", dateTime)} Expected type:<Microsoft.VisualStudio.TestPlatform.TestFramework.UnitTests.AssertTests>. Actual type:<null>.");
o.WasToStringCalled.Should().BeTrue();
}

Expand Down Expand Up @@ -108,7 +108,7 @@ public void IsInstanceOfTypeUsingGenericType_WhenValueIsNull_Fails()
{
Action action = () => Assert.IsInstanceOfType<AssertTests>(null);
action.Should().Throw<AssertFailedException>()
.WithMessage("Assert.IsInstanceOfType failed. 'value' expression: 'null'.");
.WithMessage("Assert.IsInstanceOfType failed. 'value' expression: 'null'. Expected type:<Microsoft.VisualStudio.TestPlatform.TestFramework.UnitTests.AssertTests>. Actual type:<null>.");
}

public void IsInstanceOfTypeUsingGenericType_WhenTypeMismatch_Fails()
Expand Down