Add DFTE sources and tests

test/test_template_engine/utils/test_utils.cpp

@@ -0,0 +1,62 @@
+#include "test_utils.h"
+#include <unity.h>
+#include <pgmspace.h>
+
+// Helper function to capture rendered output
+String captureRenderedOutput(TemplateContext& ctx, size_t bufferSize) {
+    String output;
+    uint8_t* buffer = new uint8_t[bufferSize];
+    
+    if (!buffer) {
+        return output;
+    }
+    
+    while (!TemplateRenderer::isComplete(ctx)) {
+        size_t written = TemplateRenderer::renderNextChunk(ctx, buffer, bufferSize);
+        if (written > 0) {
+            // Arduino String doesn't have (const char*, size_t) constructor
+            // Use substring approach or create temporary string
+            char* temp = new char[written + 1];
+            memcpy(temp, buffer, written);
+            temp[written] = '\0';
+            output += String(temp);
+            delete[] temp;
+        } else {
+            break;
+        }
+    }
+    
+    delete[] buffer;
+    return output;
+}
+
+// Helper function to compare rendered output
+bool compareRenderedOutput(const String& expected, TemplateContext& ctx, size_t bufferSize) {
+    String actual = captureRenderedOutput(ctx, bufferSize);
+    return actual == expected;
+}
+
+// Note: For test RAM getters, define them as regular functions in test files
+// Example:
+//   static String testData = "test";
+//   const char* getTestData() { return testData.c_str(); }
+
+// Helper function to verify template output
+void verifyTemplateOutput(const char* templateData, PlaceholderRegistry& registry, const String& expected) {
+    TemplateContext ctx;
+    ctx.setRegistry(&registry);
+    TemplateRenderer::initializeContext(ctx, templateData);
+    
+    String actual = captureRenderedOutput(ctx);
+    TEST_ASSERT_EQUAL_STRING_MESSAGE(expected.c_str(), actual.c_str(), 
+        "Template output should match expected");
+}
+
+// Helper function to render template to string
+String renderTemplateToString(const char* templateData, PlaceholderRegistry& registry, size_t bufferSize) {
+    TemplateContext ctx;
+    ctx.setRegistry(&registry);
+    TemplateRenderer::initializeContext(ctx, templateData);
+    return captureRenderedOutput(ctx, bufferSize);
+}
+