Function FuzzRenderExpressions

pkg/workflow/expression_extraction_fuzz_test.go:107–213

FuzzRenderExpressions fuzz-tests the combined extract-and-render pipeline against arbitrary markdown strings. It validates that the function: 1. Never panics or returns an error for arbitrary input. 2. After rendering, every ${{ ... }} expression that was extracted is replaced in the rendered output

(f *testing.F)

//     the GitHub Actions runner does at runtime) restores the mapping Content values
//     into the text so that no __GH_AW_…__ placeholder remains.
func FuzzRenderExpressions(f *testing.F) {
	// Plain markdown (no expressions)
	f.Add("This is plain text")
	f.Add("")
	f.Add("# Heading\n\nSome content.")

	// Single simple expressions
	f.Add("Repo: ${{ github.repository }}")
	f.Add("Step output: ${{ steps.sanitized.outputs.text }}")
	f.Add("Input: ${{ inputs.command }}")

	// Compound expressions
	f.Add("Data: ${{ steps.sanitized.outputs.text || inputs.command }}")
	f.Add("Data: ${{ needs.build.outputs.version && inputs.override }}")

	// Parenthesised compound expressions
	f.Add("Data: ${{ (steps.a.outputs.x || inputs.y) && inputs.z }}")
	f.Add("Data: ${{ (steps.a.outputs.x || inputs.y) && (steps.b.outputs.z || inputs.w) }}")

	// Multiple expressions in one markdown
	f.Add("Repo: ${{ github.repository }}, Actor: ${{ github.actor }}")
	f.Add("${{ steps.a.outputs.x || inputs.y }}, ${{ inputs.z }}")

	// Deprecated activation output syntax
	f.Add("Content: ${{ needs.activation.outputs.text }}")
	f.Add("Fallback: ${{ needs.activation.outputs.text || 'default' }}")

	// Malformed expressions
	f.Add("Bad: ${{ }}")
	f.Add("Unterminated: ${{ steps.a.outputs.x")

	// Expressions with string literals
	f.Add("${{ inputs.repo || 'owner/repo' }}")

	f.Fuzz(func(t *testing.T, markdown string) {
		extractor := NewExpressionExtractor()

		// Must never panic or return an error.
		mappings, err := extractor.ExtractExpressions(markdown)
		if err != nil {
			t.Errorf("ExtractExpressions(%q) returned unexpected error: %v", markdown, err)
			return
		}

		rendered := extractor.ReplaceExpressionsWithEnvVars(markdown)

		// Build a lookup: Original -> mapping.
		byOriginal := make(map[string]*ExpressionMapping, len(mappings))
		byEnvVar := make(map[string]*ExpressionMapping, len(mappings))
		for _, m := range mappings {
			byOriginal[m.Original] = m
			byEnvVar[m.EnvVar] = m
		}

		// Each mapping's Original must no longer appear verbatim in the rendered output
		// (it was replaced by the __EnvVar__ placeholder).
		for _, m := range mappings {
			if strings.Contains(rendered, m.Original) {