Squashed commit of the following:

commit 101ee55
Author: Asbelos <asbelos@btinternet.com>
Date:   Mon Aug 4 20:46:49 2025 +0100

    ZTEST2 and ZTEST3

commit 21446af
Author: Asbelos <asbelos@btinternet.com>
Date:   Fri Aug 1 22:22:45 2025 +0100

    ztest experimant

Author: Asbelos

Ztest.cpp

@@ -0,0 +1,57 @@
+#include <Arduino.h>
+#include "DIAG.h"
+#include "Ztest.h"
+#include "DCCEXParser.h"
+#include "StringFormatter.h"
+ 
+RingStream * Ztest::ring = new RingStream(128);
+   
+void Ztest::parse(const FSH * command, const FSH * expect, bool (*test)() ) {
+  
+  DIAG(F("ZTEST %S"), command);
+
+  // create copy of command in RAM
+  auto commandLength= STRLEN_P((char *)command) + 1;
+  char commandBuffer[commandLength+1];
+  STRNCPY_P(commandBuffer, (PGM_P)command,commandLength+1);
+    
+  if (expect) {
+    // create response buffer to collect comparison
+    ring->flush();
+    ring->mark(0); // mark the start of the response  
+    DCCEXParser::parseOne(ring, (byte *)commandBuffer, ring);
+    ring->commit();
+  }
+  else {
+    // run without output test
+    DCCEXParser::parseOne(& USB_SERIAL, (byte *)commandBuffer,nullptr);
+  }
+
+  
+  // test the assert of side effects
+  if (test) {
+    auto result=test();
+    DIAG(F("ZTEST assert %S"), result ? F("OK") : F("FAILED"));
+  }
+
+  if (expect) {
+    // Copy output to serial and check with expected
+    ring->read(); // read redundant client id
+    auto responseLength=ring->count();
+    if (responseLength < 1) {
+      DIAG(F("!!....(no resp) ZTEST"));
+      return; // no response
+    }
+
+    // show output while comparing
+    char output[responseLength+1];
+    for (int16_t i=0;i<responseLength;i++) output[i]=ring->read();   
+    output[responseLength]=0;
+    DIAG(F("ZTEST response:%s"), output);
+    DIAG(F("ZTEST expect  :%S"), (char *)expect);
+    if (STRCMP_P(output, (char *)expect) != 0)   
+      DIAG(F("ZTEST expect failed\n"));
+
+  }          
+  
+}

Ztest.h

@@ -0,0 +1,13 @@
+#ifndef ztest_h
+#define ztest_h
+#include "RingStream.h"
+
+class Ztest {
+  public:
+    static void parse(const FSH * command, const FSH * expect, bool (*test)() );
+    
+    private:
+     static RingStream * ring;
+};
+
+#endif