Add DFTE sources and tests

test/test_template_engine/utils/test_utils.h

@@ -0,0 +1,34 @@
+#ifndef TEST_UTILS_H
+#define TEST_UTILS_H
+
+#include <Arduino.h>
+#include <TemplateEngine.h>
+
+// Test structure and state management
+using TestFn = void(*)();
+
+struct TestCase {
+    const char* name;
+    TestFn fn;
+    uint16_t line;
+};
+
+#define TEST_ENTRY(fn) { #fn, fn, __LINE__ }
+
+// Helper function to capture rendered output
+String captureRenderedOutput(TemplateContext& ctx, size_t bufferSize = 512);
+
+// Helper function to compare rendered output
+bool compareRenderedOutput(const String& expected, TemplateContext& ctx, size_t bufferSize = 512);
+
+// Helper function to create test RAM getter
+// Note: This is a simple wrapper - for actual tests, define getter functions directly
+
+// Helper function to verify template output
+void verifyTemplateOutput(const char* templateData, PlaceholderRegistry& registry, const String& expected);
+
+// Helper function to render template to string
+String renderTemplateToString(const char* templateData, PlaceholderRegistry& registry, size_t bufferSize = 512);
+
+#endif // TEST_UTILS_H
+