VSTest Environment Variables

This document lists all environment variables that are understood and handled by the Visual Studio Test Platform (VSTest). These variables can be used to configure various aspects of test execution, debugging, diagnostics, and feature behavior.

Connection and Timeout Variables

VSTEST_CONNECTION_TIMEOUT

Description: Sets the timeout in seconds for establishing connections between various test platform components (vstest.console, testhost, datacollector).
Default: 90 seconds
Example: VSTEST_CONNECTION_TIMEOUT=120
Usage: Useful on slow machines or when network latency causes connection timeouts.

VSTEST_TESTHOST_SHUTDOWN_TIMEOUT

Description: Sets the timeout in milliseconds to wait for testhost to safely shut down.
Default: 100 milliseconds
Example: VSTEST_TESTHOST_SHUTDOWN_TIMEOUT=500
Usage: Allows testhost more time to clean up resources before forceful termination.

Diagnostics and Logging Variables

VSTEST_DIAG

Description: Enables diagnostic logging and specifies the path to the log file.
Format: Path to log directory and log file (e.g., "logs\log.txt")
Example: VSTEST_DIAG=C:\temp\logs\vstest.log
Usage: Equivalent to the --diag command line parameter.

VSTEST_DIAG_VERBOSITY

Description: Sets the verbosity level for diagnostic logging when VSTEST_DIAG is enabled.
Valid Values: Verbose, Info, Warning, Error
Default: Verbose
Example: VSTEST_DIAG_VERBOSITY=Info

VSTEST_LOGFOLDER

Description: Specifies the folder where test logs should be written.
Example: VSTEST_LOGFOLDER=C:\TestLogs

Debug Variables

VSTEST_HOST_DEBUG

Description: Enables debugging of the testhost process.
Values: Set to any non-empty value to enable
Example: VSTEST_HOST_DEBUG=1

VSTEST_HOST_DEBUG_ATTACHVS

Description: Enables debugging of the testhost process and attempts to attach Visual Studio debugger. Requires AttachVS tool (that can be built in this repo) on PATH.
Values: Set to any non-empty value to enable
Example: VSTEST_HOST_DEBUG_ATTACHVS=1

VSTEST_HOST_NATIVE_DEBUG

Description: Enables native debugging of the testhost process.
Values: Set to any non-empty value to enable
Example: VSTEST_HOST_NATIVE_DEBUG=1

VSTEST_RUNNER_DEBUG

Description: Enables debugging of the test runner (vstest.console).
Values: Set to any non-empty value to enable
Example: VSTEST_RUNNER_DEBUG=1

VSTEST_RUNNER_DEBUG_ATTACHVS

Description: Enables debugging of the test runner and attempts to attach Visual Studio debugger. Requires AttachVS tool (that can be built in this repo) on PATH.
Values: Set to any non-empty value to enable
Example: VSTEST_RUNNER_DEBUG_ATTACHVS=1

VSTEST_RUNNER_NATIVE_DEBUG

Description: Enables native debugging of the test runner.
Values: Set to any non-empty value to enable
Example: VSTEST_RUNNER_NATIVE_DEBUG=1

VSTEST_DATACOLLECTOR_DEBUG

Description: Enables debugging of data collector processes.
Values: Set to any non-empty value to enable
Example: VSTEST_DATACOLLECTOR_DEBUG=1

VSTEST_DATACOLLECTOR_DEBUG_ATTACHVS

Description: Enables debugging of data collector processes and attempts to attach Visual Studio debugger.
Values: Set to any non-empty value to enable
Example: VSTEST_DATACOLLECTOR_DEBUG_ATTACHVS=1

VSTEST_BLAMEDATACOLLECTOR_DEBUG

Description: Enables debugging of the blame data collector.
Values: Set to any non-empty value to enable
Example: VSTEST_BLAMEDATACOLLECTOR_DEBUG=1

VSTEST_DUMPTOOL_DEBUG

Description: Enables debugging of dump collection tools.
Values: Set to any non-empty value to enable
Example: VSTEST_DUMPTOOL_DEBUG=1

VSTEST_DEBUG_ATTACHVS_PATH

Description: Specifies the path for AttachVS tool, when not found on PATH. AttachVS tool can be built from this repo.
Example: VSTEST_DEBUG_ATTACHVS_PATH=C:\Program Files\Microsoft Visual Studio\2022\Enterprise\Common7\IDE\devenv.exe

VSTEST_DEBUG_NOBP

Description: Disables breakpoints on executable entry points, to for more seemless debugging when using AttachVS.
Values: Set to "1" to disable breakpoints
Example: VSTEST_DEBUG_NOBP=1

Crash Dump and Blame Collection Variables

VSTEST_DUMP_PATH

Description: Overrides the default directory where crash dumps are stored. This disables automatic dump upload via attachments.
Example: VSTEST_DUMP_PATH=C:\CrashDumps

VSTEST_DUMP_TEMP_PATH

Description: Specifies the temporary directory for dump collection operations.
Fallback: Falls back to AGENT_TEMPDIRECTORY, then system temp directory
Example: VSTEST_DUMP_TEMP_PATH=C:\temp\dumps

VSTEST_DUMP_FORCEPROCDUMP

Description: Forces the use of ProcDump for crash dump collection.
Values: Set to any non-empty value to enable
Example: VSTEST_DUMP_FORCEPROCDUMP=1

VSTEST_DUMP_FORCENETDUMP

Description: Forces the use of dotnet-dump for crash dump collection.
Values: Set to any non-empty value to enable
Example: VSTEST_DUMP_FORCENETDUMP=1

VSTEST_DUMP_PROCDUMPARGUMENTS

Description: Specifies custom arguments for ProcDump when collecting crash dumps.
Example: VSTEST_DUMP_PROCDUMPARGUMENTS=-e 1 -g -t -ma

VSTEST_DUMP_PROCDUMPADDITIONALARGUMENTS

Description: Specifies additional arguments to append to ProcDump command line.
Example: VSTEST_DUMP_PROCDUMPADDITIONALARGUMENTS=-r

Feature Control Variables (Disable Features)

VSTEST_DISABLE_ARTIFACTS_POSTPROCESSING

Description: Disables artifact post-processing functionality.
Values: Set to any non-zero value to disable
Example: VSTEST_DISABLE_ARTIFACTS_POSTPROCESSING=1
Added: Version 17.2-preview, 7.0-preview

VSTEST_DISABLE_ARTIFACTS_POSTPROCESSING_NEW_SDK_UX

Description: Disables new SDK UX for artifact post-processing, showing old output format.
Values: Set to any non-zero value to disable
Example: VSTEST_DISABLE_ARTIFACTS_POSTPROCESSING_NEW_SDK_UX=1
Usage: Useful when parsing console output and need to maintain compatibility
Added: Version 17.2-preview, 7.0-preview

VSTEST_DISABLE_FASTER_JSON_SERIALIZATION

Description: Disables the faster JSON serialization mechanism and falls back to standard serialization.
Values: Set to any non-zero value to disable
Example: VSTEST_DISABLE_FASTER_JSON_SERIALIZATION=1

VSTEST_DISABLE_MULTI_TFM_RUN

Description: Forces vstest.console to run all sources using the same target framework (TFM) and architecture instead of allowing multiple different TFMs and architectures to run simultaneously.
Values: Set to any non-zero value to disable
Example: VSTEST_DISABLE_MULTI_TFM_RUN=1

VSTEST_DISABLE_SERIALTESTRUN_DECORATOR

Description: Disables the SerialTestRun decorator.
Values: Set to any non-zero value to disable
Example: VSTEST_DISABLE_SERIALTESTRUN_DECORATOR=1

VSTEST_DISABLE_SHARING_NETFRAMEWORK_TESTHOST

Description: Disables sharing of .NET Framework testhosts, returning to the behavior of sharing testhosts when they are running .NET Framework DLLs and are not disabling appdomains or running in parallel.
Values: Set to any non-zero value to disable
Example: VSTEST_DISABLE_SHARING_NETFRAMEWORK_TESTHOST=1

VSTEST_DISABLE_STANDARD_OUTPUT_CAPTURING

Description: Disables capturing standard output from testhost processes.
Values: Set to any non-zero value to disable
Example: VSTEST_DISABLE_STANDARD_OUTPUT_CAPTURING=1

VSTEST_DISABLE_STANDARD_OUTPUT_FORWARDING

Description: Disables forwarding standard output from testhost processes.
Values: Set to any non-zero value to disable
Example: VSTEST_DISABLE_STANDARD_OUTPUT_FORWARDING=1

VSTEST_DISABLE_THREADPOOL_SIZE_INCREASE

Description: Disables setting a higher value for ThreadPool.SetMinThreads. The higher value allows testhost to connect back faster by avoiding waits for ThreadPool to start more threads.
Values: Set to any non-zero value to disable
Example: VSTEST_DISABLE_THREADPOOL_SIZE_INCREASE=1

VSTEST_DISABLE_UTF8_CONSOLE_ENCODING

Description: Disables setting UTF-8 encoding in console output.
Values: Set to "1" to disable
Example: VSTEST_DISABLE_UTF8_CONSOLE_ENCODING=1

Build and MSBuild Integration Variables

VSTEST_BUILD_DEBUG

Description: Enables debug output for VSTest build tasks.
Values: Set to any non-empty value to enable
Example: VSTEST_BUILD_DEBUG=1

VSTEST_BUILD_TRACE

Description: Enables trace output for VSTest build tasks.
Values: Set to any non-empty value to enable
Example: VSTEST_BUILD_TRACE=1

VSTEST_MSBUILD_NOLOGO

Description: Suppresses the display of the copyright banner when running tests via MSBuild.
Values: Set to "1" to suppress logo
Example: VSTEST_MSBUILD_NOLOGO=1

Telemetry Variables

VSTEST_TELEMETRY_OPTEDIN

Description: Controls whether telemetry data is collected and sent.
Values: Set to "1" to opt in, any other value opts out
Example: VSTEST_TELEMETRY_OPTEDIN=1

VSTEST_LOGTELEMETRY

Description: Enables logging of telemetry data to files.
Values: Set to any non-empty value to enable
Example: VSTEST_LOGTELEMETRY=1

VSTEST_LOGTELEMETRY_PATH

Description: Specifies the directory where telemetry log files should be written.
Example: VSTEST_LOGTELEMETRY_PATH=C:\TelemetryLogs

Performance and Parallelization Variables

VSTEST_HOSTPRESTART_COUNT

Description: Sets the number of testhosts to pre-start for improved performance in parallel test execution.
Format: Integer value
Example: VSTEST_HOSTPRESTART_COUNT=4

Configuration and Path Variables

VSTEST_CONSOLE_PATH

Description: Specifies the path to the vstest.console executable.
Example: VSTEST_CONSOLE_PATH=C:\Tools\VSTest\vstest.console.exe

VSTEST_IGNORE_DOTNET_ROOT

Description: When set to a non-zero value, ignores the DOTNET_ROOT environment variable during testhost selection.
Values: Set to any non-zero value to ignore DOTNET_ROOT
Default: "0" (respects DOTNET_ROOT)
Example: VSTEST_IGNORE_DOTNET_ROOT=1

VSTEST_SKIP_FAKES_CONFIGURATION

Description: Skips Microsoft Fakes configuration during test execution.
Values: Set to "1" to skip
Example: VSTEST_SKIP_FAKES_CONFIGURATION=1

UWP (Universal Windows Platform) Variables

VSTEST_UWP_DEPLOY_LOCAL_PATH

Description: Overrides the local path for UWP application deployment.
Example: VSTEST_UWP_DEPLOY_LOCAL_PATH=C:\UWPApps\LocalDeploy

VSTEST_UWP_DEPLOY_REMOTE_PATH

Description: Overrides the remote path for UWP application deployment.
Example: VSTEST_UWP_DEPLOY_REMOTE_PATH=\\RemoteDevice\Deploy

Windows App Host Variables

VSTEST_WINAPPHOST_*

Description: Various environment variables related to Windows App Host configuration.
Pattern: Variables following the pattern VSTEST_WINAPPHOST_{VARIABLE_NAME}
Usage: Used internally for Windows App Host test execution scenarios

Legacy/Experimental Variables

VSTEST_EXPERIMENTAL_FORWARD_OUTPUT_FEATURE

Description: (Deprecated) Previously used to enable output forwarding feature.
Status: Replaced by VSTEST_DISABLE_STANDARD_OUTPUT_CAPTURING and VSTEST_DISABLE_STANDARD_OUTPUT_FORWARDING
Note: This variable is no longer used as the feature is now enabled by default

VSTEST_DISABLE_PROTOCOL_3_VERSION_DOWNGRADE

Description: Disables automatic downgrade to protocol version 3 for compatibility.
Values: Set to any non-empty value to disable downgrade
Example: VSTEST_DISABLE_PROTOCOL_3_VERSION_DOWNGRADE=1

Usage Examples

Debugging a Test Run

# Enable testhost debugging and increase connection timeout
set VSTEST_HOST_DEBUG=1
set VSTEST_CONNECTION_TIMEOUT=300
dotnet test MyTests.dll

Collecting Diagnostics

# Enable detailed diagnostic logging
set VSTEST_DIAG=C:\temp\vstest.log
set VSTEST_DIAG_VERBOSITY=Verbose
dotnet test MyTests.dll

Performance Optimization

# Pre-start testhosts for better parallel performance
set VSTEST_HOSTPRESTART_COUNT=4
dotnet test MyTests.dll --parallel

Crash Dump Collection

# Configure crash dump collection
set VSTEST_DUMP_PATH=C:\CrashDumps
set VSTEST_DUMP_FORCEPROCDUMP=1
dotnet test MyTests.dll --collect:"blame;collectdump=true"

Notes

Most debug variables require only being set to any non-empty value to be enabled.
Feature disable variables typically use "1" or any non-zero value to disable the feature.
Connection timeout values are in seconds unless otherwise specified.
Paths should use the appropriate path separator for your operating system.
Some variables are only effective in specific scenarios (e.g., UWP variables only apply to UWP test projects).

For more information about VSTest and its features, see the VSTest documentation.

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!