What causes "couldn't generate assertion: %w" in crowdsecurity/crowdsec?

Run the hubtest with auto-generation enabled to populate the assert file from a successful parse run

couldn't generate assertion: %w

Error message

couldn't generate assertion: %w

What it means

When the parser assert file exists but is empty (size 0), hubtest auto-generates assertions from the parser results dump (ParserResultFile). This error wraps any failure of AutoGenFromFile, typically because the results file is missing or unreadable.

Source

Thrown at pkg/hubtest/hubtest_item.go:536

		_, err := os.Stat(t.ParserAssert.File)
		if os.IsNotExist(err) {
			parserAssertFile, err := os.Create(t.ParserAssert.File)
			if err != nil {
				return err
			}

			parserAssertFile.Close()
		}

		assertFileStat, err := os.Stat(t.ParserAssert.File)
		if err != nil {
			return fmt.Errorf("error while stats '%s': %w", t.ParserAssert.File, err)
		}

		if assertFileStat.Size() == 0 {
			assertData, err := t.ParserAssert.AutoGenFromFile(t.ParserResultFile)
			if err != nil {
				return fmt.Errorf("couldn't generate assertion: %w", err)
			}

			t.ParserAssert.AutoGenAssertData = assertData
			t.ParserAssert.AutoGenAssert = true
		} else {
			if err := t.ParserAssert.AssertFile(t.ParserResultFile); err != nil {
				// TODO: no error - should not prevent running the other tests
				return fmt.Errorf("unable to run assertion on file '%s': %w", t.ParserResultFile, err)
			}
		}
	}

	// assert scenarios
	nbScenario := 0

	for _, scenario := range t.Config.Scenarios {
		if scenario == "" {
			continue

View on GitHub (pinned to 909b515798)

Solutions

Run the hubtest with auto-generation enabled to populate the assert file from a successful parse run
Ensure the crowdsec parse step completed and wrote t.ParserResultFile
Check permissions and path of the results directory

Example fix

// before: empty parser_assert.yaml committed
// after: generate it
./tests/crowdsec -c tests/test01/runtime.yaml -dump-data tests/test01/results && regenerate asserts

Defensive patterns

Strategy: validation

Validate before calling

if st, err := os.Stat(parserResultFile); err != nil || st.Size() == 0 { t.Fatalf("parser results missing/empty at %s", parserResultFile) }

Try / catch

if err := t.Run(ctx); err != nil && strings.Contains(err.Error(), "couldn't generate assertion") { /* ensure parse ran and dump exists, retry */ }

Prevention

Never commit empty assert files without an autogen step in CI
Ensure the parse step completes before assertion autogen
Keep results dir intact during the test run

When it happens

Trigger: RunWithLogFile: parser_assert.yaml is 0 bytes and ParserAssert.AutoGenFromFile(t.ParserResultFile) fails — e.g. results dump absent because the parse step produced nothing or dump-data target was removed.

Common situations: Empty assert file committed without ever running autogen; results directory cleaned between the parse and assert steps; parse run silently produced no output so the results file was never created.

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

AI-assisted analysis of crowdsecurity/crowdsec@909b515798 (2026-09-06). Data as JSON: /api/errors/28c77f1f9c2b1fb7. Report an issue: GitHub.