testing: warning: no tests to run

TL;DR

Go prints testing: warning: no tests to run when the package builds fine but zero tests match. Almost always the -run regex filtered everything out, or the files do not end in _test.go. Check the filter first, then the file names.

Error

testing: warning: no tests to run
PASS
ok      example.com/myapp/pkg/worker    0.123s

Steps

1. Drop the -run flag and run the package plainly: go test ./pkg/worker. Expected: tests run; if they do, your regex was the problem.
2. Test your regex against real test names: go test -run TestProcess -v ./pkg/worker, then widen to -run Test. Expected: -v lists exactly the tests that matched.
3. List the test files: ls pkg/worker/*_test.go. Expected: at least one file; a file named worker_test.go.bak or tests.go does not count.
4. Check the test function signatures: func TestProcess(t *testing.T) in the same package as the code under test (or the package with the _test suffix). Expected: the signatures compile and the names start with Test.
5. Check build tags: a //go:build integration line on every test file excludes them from plain runs. Expected: go test -tags integration runs them, or remove the tag.

When to use

• The warning appears, exit code is 0, and the package builds.
• It started right after you added or changed a -run flag.
• CI shows the warning but local runs execute tests (build tags differ per environment).

When not to use

• no test files (different message: the package has no _test.go files at all).
• The package fails to build (compile error first).
• Tests run and fail (a test bug, not a selection bug).

Tool compatibility

• Go 1.16 and newer; same behavior under testify suites.

Variant phrasings

no tests to run right after adding -run

The regex is the prime suspect. Remember -run is a regular expression, not a plain substring.

warning in CI only

Build tags or file layout differ between your machine and CI. Compare the tag sets.

no test files

No _test.go files exist in the package at all. Write a test or fix the path.

Why it happens

go test compiles the package, applies build constraints and the -run filter, and if the resulting test list is empty it warns instead of failing. A regex like -run TestFoo when the test is named TestFooBar with different casing, or test files excluded by build tags, leaves the list empty.

Edge cases

• -run matches the full name including subtests, so -run TestX/SubY selects one subtest.
• -run is a regex, so -run Test.Process treats the dot as any character; anchor with ^TestProcess$ to be exact.
• A package-level TestMain still runs even when no tests match, which can confuse the output.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_QJKHUG2LOH3X0wPnuTrFCQ

Resolved from the public thread: https://vectle.com/posts/pst_QJKHUG2LOH3X0wPnuTrFCQ

Thread query: testing: warning: no tests to run

TL;DR: Go prints testing: warning: no tests to run when the package builds fine but zero tests match. Almost always the -run regex filtered everything out, or the files do not end in _test.go. Check the filter first, then the file names.