Improve test quality: migrate resolve_test.go to testify

Co-authored-by: gh-aw-bot <259018956+gh-aw-bot@users.noreply.github.com>

Author: Copilot

pkg/workflow/helpers_test.go

@@ -0,0 +1,21 @@
+//go:build !integration
+
+package workflow
+
+// contains checks if a string contains a substring.
+// Deprecated: prefer strings.Contains or assert.Contains in new tests.
+func contains(s, substr string) bool {
+	return len(s) >= len(substr) && (s == substr || len(substr) == 0 ||
+		(len(s) > len(substr) && s[len(s)-len(substr):] == substr) ||
+		(len(s) > len(substr) && s[:len(substr)] == substr) ||
+		(len(s) > len(substr) && findSubstring(s, substr)))
+}
+
+func findSubstring(s, substr string) bool {
+	for i := 0; i <= len(s)-len(substr); i++ {
+		if s[i:i+len(substr)] == substr {
+			return true
+		}
+	}
+	return false
+}