migrate-mstest-v1v2-to-v3

Original：🇺🇸 English

Translated

Migrate MSTest v1 or v2 test project to MSTest v3. Use when user says "upgrade MSTest", "upgrade to MSTest v3", "migrate to MSTest v3", "update test framework", "modernize tests", "MSTest v3 migration", "MSTest compatibility", "MSTest v2 to v3", or build errors after updating MSTest packages from 1.x/2.x to 3.x. USE FOR: upgrading from MSTest v1 assembly references (Microsoft.VisualStudio.QualityTools.UnitTestFramework) or MSTest v2 NuGet (MSTest.TestFramework 1.x-2.x) to MSTest v3, fixing assertion overload errors (AreEqual/AreNotEqual), updating DataRow constructors, replacing .testsettings with .runsettings, timeout behavior changes, target framework compatibility (.NET 5 dropped -- use .NET 6+; .NET Fx older than 4.6.2 dropped), adopting MSTest.Sdk. First step toward MSTest v4 -- after this, use migrate-mstest-v3-to-v4. DO NOT USE FOR: migrating to MSTest v4 (use migrate-mstest-v3-to-v4), migrating between frameworks (MSTest to xUnit/NUnit), or general .NET upgrades unrelated to MSTest.

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Sourcedotnet/skills

Added on2026-04-10

NPX Install

npx skill4agent add dotnet/skills migrate-mstest-v1v2-to-v3

SKILL.md Content

View Translation Comparison →

MSTest v1/v2 -> v3 Migration

Migrate a test project from MSTest v1 (assembly references) or MSTest v2 (NuGet 1.x-2.x) to MSTest v3. MSTest v3 is not binary compatible with v1/v2 -- libraries compiled against v1/v2 must be recompiled.

When to Use

Project references

Microsoft.VisualStudio.QualityTools.UnitTestFramework.dll

(MSTest v1)

Project uses
```
MSTest.TestFramework
```
/
```
MSTest.TestAdapter
```
NuGet 1.x or 2.x
Resolving build errors after updating MSTest packages from v1/v2 to v3
Replacing
```
.testsettings
```
with
```
.runsettings
```
Adopting MSTest.Sdk or in-assembly parallel execution

When Not to Use

Project already uses MSTest v3 (3.x packages)
Upgrading v3 to v4 -- use
```
migrate-mstest-v3-to-v4
```
Migrating between frameworks (MSTest to xUnit/NUnit)

Inputs

Input	Required	Description
Project or solution path	Yes	The `.csproj` , `.sln` , or `.slnx` entry point containing MSTest test projects
Build command	No	How to build (e.g., `dotnet build` , a repo build script). Auto-detect if not provided
Test command	No	How to run tests (e.g., `dotnet test` ). Auto-detect if not provided

Breaking Changes Summary

MSTest v3 introduces these breaking changes from v1/v2. Address only the ones relevant to the project:

Breaking Change	Impact	Fix
`Assert.AreEqual(object, object)` overload removed	Compile error on untyped assertions	Add generic type: `Assert.AreEqual<T>(expected, actual)` . Same for `AreNotEqual` , `AreSame` , `AreNotSame`
`DataRow` strict type matching	Runtime/compile errors when argument types don't match parameter types exactly	Change literals to exact types: `1` for int, `1L` for long, `1.0f` for float
`DataRow` max 16 constructor parameters (early v3)	Compile error if >16 args; fixed in later v3 versions	Update to latest 3.x, or refactor test / wrap extra params in array
`.testsettings` / `<LegacySettings>` no longer supported	Settings silently ignored	Delete `.testsettings` , create `.runsettings` with equivalent config
Timeout behavior unified across .NET Core / Framework	Tests with `[Timeout]` may behave differently	Verify timeout values; adjust if needed
Dropped target frameworks: .NET 5, .NET Fx < 4.6.2, netstandard1.0, UWP < 16299, WinUI < 18362	Build error	Update TFM: .NET 5 -> net8.0 (LTS) or net6.0+, netfx -> net462+, netstandard1.0 -> netstandard2.0. Note: net6.0, net8.0, net9.0 are all supported
Not binary compatible with v1/v2	Libraries compiled against v1/v2 must be recompiled	Recompile all dependencies against v3

Response Guidelines

Always identify the current version first: Before recommending any migration steps, explicitly state the current MSTest version detected in the project (e.g., "Your project uses MSTest v2 (2.2.10)" or "This is an MSTest v1 project using QualityTools assembly references"). This grounds the migration advice and confirms you've read the project files.
Focused fix requests (user has specific compilation errors after upgrading): Address only the relevant breaking change from the table above. Show a concise before/after fix. Do not walk through the full migration workflow.
Specific feature migration (user asks about one aspect like .testsettings, DataRow, or assertions): Address only that specific aspect with a concrete fix. Do not walk through the entire migration workflow or unrelated breaking changes.
"What to expect" questions (user asks about breaking changes before upgrading): Present only the breaking changes that are clearly relevant to the user's visible code and configuration. For each, give a one-line fix summary. Do not include every possible breaking change -- only the ones that apply. Do not walk through the full workflow.
Full migration requests (user wants complete migration): Follow the complete workflow below.
Comparison questions (user asks about v1 vs v2 differences): Explain concisely -- v1 uses assembly references and requires removing them first; v2 uses NuGet and just needs a version bump. Both converge on the same v3 packages and breaking changes.

Migration Paths

MSTest v1 (assembly reference to QualityTools): Remove the assembly reference (Step 2), add v3 NuGet packages (Step 3), fix breaking changes (Step 5).
MSTest v2 (NuGet packages 1.x-2.x): Update package versions to 3.x (Step 3), fix breaking changes (Step 5). No assembly reference removal needed.

Both paths converge at Step 3 -- the same v3 packages and breaking changes apply regardless of starting version.

Workflow

Step 1: Assess the project

Identify which MSTest version is currently in use:
- Assembly reference: Look for
```
Microsoft.VisualStudio.QualityTools.UnitTestFramework
```
  in project references -> MSTest v1
- NuGet packages: Check
```
MSTest.TestFramework
```
  and
```
MSTest.TestAdapter
```
  package versions -> v1 if 1.x, v2 if 2.x
Check if the project uses a
```
.testsettings
```
file (indicated by
```
<LegacySettings>
```
in test configuration)
Check if the target framework is dropped in v3 (see Step 4)
Run a clean build to establish a baseline of existing errors/warnings

Step 2: Remove v1 assembly references (if applicable)

If the project uses MSTest v1 via assembly references:

Remove the reference to
```
Microsoft.VisualStudio.QualityTools.UnitTestFramework.dll
```
- In SDK-style projects, remove the
```
<Reference>
```
  element from the
```
.csproj
```
- In non-SDK-style projects, remove via Visual Studio Solution Explorer -> References -> right-click -> Remove
Save the project file

Step 3: Update packages to MSTest v3

Choose one of these approaches:

Option A -- Install the MSTest metapackage (recommended):

Remove individual

MSTest.TestFramework

and

MSTest.TestAdapter

package references and replace with the unified

MSTest

metapackage:

xml

<PackageReference Include="MSTest" Version="3.8.0" />

Also ensure

Microsoft.NET.Test.Sdk

is referenced (or update individual

MSTest.TestFramework

+

MSTest.TestAdapter

packages to 3.8.0 if you prefer not using the metapackage).

Option B -- Use MSTest.Sdk (SDK-style projects only):

Change

<Project Sdk="Microsoft.NET.Sdk">

to

<Project Sdk="MSTest.Sdk/3.8.0">

. MSTest.Sdk automatically provides MSTest.TestFramework, MSTest.TestAdapter, MSTest.Analyzers, and Microsoft.NET.Test.Sdk.

Important: MSTest.Sdk defaults to Microsoft.Testing.Platform (MTP) instead of VSTest. For VSTest compatibility (e.g.,
vstest.console
in CI), add
<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.13.0" />
.

When switching to MSTest.Sdk, remove these (SDK provides them automatically):

Packages:

MSTest

,

MSTest.TestFramework

,

MSTest.TestAdapter

,

MSTest.Analyzers

,

Microsoft.NET.Test.Sdk

Properties:

<EnableMSTestRunner>

,

<OutputType>Exe</OutputType>

,

<IsPackable>false</IsPackable>

,

<IsTestProject>true</IsTestProject>

Step 4: Update target frameworks if needed

MSTest v3 supports .NET 6+, .NET Core 3.1, .NET Framework 4.6.2+, .NET Standard 2.0, UWP 16299+, and WinUI 18362+. If the project targets a dropped framework version, update to a supported one:

Dropped	Recommended replacement
.NET 5	.NET 8.0 (current LTS) or .NET 6+
.NET Framework < 4.6.2	.NET Framework 4.6.2
.NET Standard 1.0	.NET Standard 2.0
UWP < 16299	UWP 16299
WinUI < 18362	WinUI 18362

Note: .NET 6, .NET 8, and .NET 9 are all supported by MSTest v3. Do not change TFMs that are already supported.

Step 5: Resolve build errors and breaking changes

Run

dotnet build

and fix errors using the Breaking Changes Summary above. Key fixes:

Assertion overloads -- MSTest v3 removed

Assert.AreEqual(object, object)

and

Assert.AreNotEqual(object, object)

. Add explicit generic type parameters:

csharp

// Before (v1/v2)                           // After (v3)
Assert.AreEqual(expected, actual);        -> Assert.AreEqual<MyType>(expected, actual);
Assert.AreNotEqual(a, b);                -> Assert.AreNotEqual<MyType>(a, b);
Assert.AreSame(expected, actual);         -> Assert.AreSame<MyType>(expected, actual);

DataRow strict type matching -- argument types must exactly match parameter types. Implicit conversions that worked in v2 fail in v3:

csharp

// Error: 1L (long) won't convert to int parameter -> fix: use 1 (int)
// Error: 1.0 (double) won't convert to float parameter -> fix: use 1.0f (float)

Timeout behavior -- unified across .NET Core and .NET Framework. Verify

[Timeout]

values still work.

Step 6: Replace .testsettings with .runsettings

The

.testsettings

file and

<LegacySettings>

are no longer supported in MSTest v3. Delete the
.testsettings
file and create a

.runsettings

file -- do not keep both.

Key mappings:

.testsettings	.runsettings equivalent
`TestTimeout` property	`<MSTest><TestTimeout>30000</TestTimeout></MSTest>`
Deployment config	`<MSTest><DeploymentEnabled>true</DeploymentEnabled></MSTest>` or remove
Assembly resolution settings	Remove -- not needed in modern .NET
Data collectors	`<DataCollectionRunSettings><DataCollectors>` section

Important: Map timeout to
<MSTest><TestTimeout>
(per-test), not
<TestSessionTimeout>
(session-wide). Remove
<LegacySettings>
entirely.

Step 7: Verify

Run
```
dotnet build
```
-- confirm zero errors and review any new warnings
Run
```
dotnet test
```
-- confirm all tests pass
Compare test results (pass/fail counts) to the pre-migration baseline
Check that no tests were silently dropped due to discovery changes

Validation

MSTest v3 packages (or MSTest.Sdk) correctly referenced; v1/v2 references removed
Project builds with zero errors
All tests pass (
```
dotnet test
```
) -- compare pass/fail counts to pre-migration baseline
```
.testsettings
```
replaced with
```
.runsettings
```
(if applicable)

Next Step

After v3 migration, use

migrate-mstest-v3-to-v4

for MSTest v4.

Common Pitfalls

Pitfall	Solution
Missing `Microsoft.NET.Test.Sdk`	Add package reference -- required for test discovery with VSTest
MSTest.Sdk tests not found by `vstest.console`	MSTest.Sdk defaults to Microsoft.Testing.Platform; add explicit `Microsoft.NET.Test.Sdk` for VSTest compatibility