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The nf-test.config file is a configuration file used to customize settings and behavior for nf-test. This file must be located in the root of your project, and it is automatically loaded when you run nf-test test. Below are the parameters that can be adapted:

Parameter Description Default Value
testsDir Location for storing all nf-test cases (test scripts). If you want all test files to be in the same directory as the script itself, you can set the testDir to . "tests"
workDir Directory for storing temporary files and working directories for each test. This directory should be added to .gitignore. ".nf-test"
configFile Location of an optional nextflow.config file specifically used for executing tests. Learn more. "tests/nextflow.config"
libDir Location of a library folder that is automatically added to the classpath during testing to include additional libraries or resources needed for test cases. "tests/lib"
profile Default profile to use for running tests defined in the Nextflow configuration. See Learn more. "docker"
withTrace Enable or disable tracing options during testing. Disable tracing if your containers don't include the procps tool. true
autoSort Enable or disable sorted channels by default when running tests. true
options Custom Nextflow command-line options to be applied when running tests. For example "-dump-channels -stub-run"

Here's an example of what an nf-test.config file could look like:

config {
    testsDir "tests"
    workDir ".nf-test"
    configFile "tests/nextflow.config"
    libDir "tests/lib"
    profile "docker"
    withTrace false
    autoSort false
    options "-dump-channels -stub-run"


This optional nextflow.config file is used to execute tests. This is a good place to set default params for all your tests. Example number of threads:

params {
    // run all tests with 1 threads
    threads = 1

Configuration for tests

nf-test allows to set and overwrite the config, autoSort and options properties for a specific testsuite:

nextflow_process {

    name "Test Process..."
    script ""
    process "my_process"
    config "path/to/test/nextflow.config"
    autoSort false
    options "-dump-channels"


It is also possible to overwrite these properties for specific test. Depending on the used Nextflow option, also add the --debug nf-test option on the command-line to see the addtional output.

nextflow_process {

   test("my test") {

      config "path/to/test/nextflow.config"
      autoSort false
      options "-dump-channels"



Managing Profiles

Profiles in nf-test provide a convenient way to configure and customize Nextflow executions for your test cases. To run your test using a specific Nextflow profile, you can use the --profile argument on the command line or define a default profile in nf-test.config.

Basic Profile Usage

By default, nf-test reads the profile configuration from nf-test.config. If you've defined a profile called A in nf-test.config, running nf-test --profile B will start Nextflow with only the B profile. It replaces any existing profiles.

Combining Profiles with "+"

To combine profiles, you can use the + prefix. For example, running nf-test --profile +B will start Nextflow with both A and B profiles, resulting in -profile A,B. This allows you to extend the existing configuration with additional profiles.

Profile Priority Order

Profiles are evaluated in a specific order, ensuring predictable behavior:

  1. Profile in nf-test.config: The first profile considered is the one defined in nf-test.config.

  2. Profile Defined in Testcase: If you specify a profile within a testcase, it takes precedence over the one in nf-test.config.

  3. Profile Defined on the Command Line (CLI): Finally, any profiles provided directly through the CLI have the highest priority and override/extends previously defined profiles.

By understanding this profile evaluation order, you can effectively configure Nextflow executions for your test cases in a flexible and organized manner.

File Staging

The stage section of the nf-test.config file is used to define files that are needed by Nextflow in the test environment (meta directory). Additionally, the directories lib, bin, and assets are automatically staged.

Supported Directives

This directive is used to create symbolic links (symlinks) in the test environment. Symlinks are pointers to files or directories and can be useful for creating references to data files or directories required for the test. The syntax for the symlink directive is as follows:

symlink "source_path"

source_path: The path to the source file or directory that you want to symlink.


This directive is used to copy files or directories into the test environment. It allows you to duplicate files from a specified source to a location within the test environment. The syntax for the copy directive is as follows:

copy "source_path"

source_path: The path to the source file or directory that you want to copy.

Example Usage

Here's an example of how to use the stage section in an nf-test.config file:

config {
    stage {
        symlink "data/original_data.txt"
        copy "resources/config.yml"

In this example:

  • The symlink directive creates a symlink named "original_data.txt" in the meta directory pointing to the file located at "data/original_data.txt."
  • The copy directive copies the "config.yml" file from the "resources" directory to the meta directory.


Furthermore, it is also possible to stage files that are specific to a single testsuite:

nextflow_workflow {

    name "Test workflow HELLO_WORKFLOW"

    script "./"
    workflow "HELLO_WORKFLOW"

    stage {
        symlink "test-assets/test.txt"

    test("Should print out test file") {
        expect {
            assert workflow.success