TestRunner integration

JETLS integrates with TestRunner.jl to provide an enhanced testing experience directly within your editor. This feature allows you to run individual @testset blocks directly from your development environment.

Prerequisites

To use this feature, you need to install the testrunner executable:

julia -e 'using Pkg; Pkg.Apps.add(; url="https://github.com/aviatesk/TestRunner.jl", rev="release")'

Note that you need to manually make ~/.julia/bin available on the PATH environment for the testrunner executable to be accessible. See https://pkgdocs.julialang.org/dev/apps/ for the details.

Features

Code lens

When you open a Julia file containing @testset blocks, JETLS displays interactive code lenses above each @testset:

• ▶ Run "testset_name": Run the testset for the first time

After running tests, the code lens is refreshed as follows:

• ▶ Rerun "testset_name" [summary]: Re-run a testset that has previous results
• ☰ Open logs: View the detailed test output in a new editor tab
• ✓ Clear result: Remove the test results and inline diagnostics

Code actions

You can trigger test runs via "code actions" that are explicitly requested by the user:

• Inside a @testset block: Run the entire testset

• On an individual @test macro: Run just that specific test case

Note that when running individual @test cases, the error results are displayed as temporary diagnostics for 10 seconds. Click ☰ Open logs button in the pop up message to view detailed error messages that persist.

Test diagnostics

Failed tests are displayed as diagnostics (red squiggly lines) at the exact lines where the failures occurred, making it easy to identify and fix issues:

Progress notifications

For clients that support work done progress, JETLS shows progress notifications while tests are running, keeping you informed about long-running test suites.

Supported patterns

The TestRunner integration supports:

1. Named @testset blocks (via code lens or code actions):

   using Test
   
   # supported: named `@testset`
   @testset "foo" begin
     @test sin(0) == 0
     @test sin(Inf) == 0
     @test_throws ErrorException sin(Inf) == 0
     @test cos(π) == -1
   
       # supported: nested named `@testset`
       @testset "bar" begin
         @test sin(π) == 0
         @test sin(0) == 1
         @test cos(Inf) == -1
       end
   end
   
   # unsupported: `@testset` inside function definition
   function test_func1()
     @testset "inside function" begin
       @test true
     end
   end
   
   # supported: this pattern is fine
   function test_func2()
     @testset "inside function" begin
       @test true
     end
   end
   @testset "test_func2" test_func2()

2. Individual @test macros (via code actions only):

   # Run individual tests directly
   @test 1 + 1 == 2
   @test sqrt(4) ≈ 2.0
   
   # Also works inside testsets
   @testset "math tests" begin
     @test sin(0) == 0  # Can run just this test
     @test cos(π) == -1  # Or just this one
   end
   
   # Multi-line `@test` expressions are just fine
   @test begin
     x = complex_calculation()
     validate(x)
   end
   
   # Other Test.jl macros are supported too
   @test_throws DomainErrors sin(Inf)

See the TestRunner.jl README for more details.

Troubleshooting

If you see an error about testrunner not being found:

1. Ensure you've installed TestRunner.jl as described above
2. Check that testrunner is in your system PATH by running which testrunner: otherwise you may need to add ~/.julia/bin to PATH
3. Restart your editor to ensure it picks up the updated PATH

Starting with releases on or after 2026-05-06, test execution streams the current editor buffer to testrunner over stdin, so saving the file is not required and unsaved edits run as-is — including buffers (untitled: for VSCode / buffer: for Sublime Text) that have never been saved to disk, where relative include calls resolve from the workspace root.

This needs a testrunner CLI new enough to recognize the --read-stdin flag — if tests fail to start with an "Unknown option" error, reinstall testrunner (see Prerequisites) and confirm that testrunner --help lists --read-stdin under Options:.