CI: erase nvs partition before test:

Latest NVS partition bin can't be parsed by old IDF revision. Need to erase before test.

tools/tiny-test-fw/IDF/IDFDUT.py

@@ -17,6 +17,10 @@ import os
 import re
 import subprocess
 import functools
+import random
+import tempfile
+
+from serial.tools import list_ports
 
 import DUT
 
@@ -40,6 +44,8 @@ class IDFDUT(DUT.SerialDUT):
     """ IDF DUT, extends serial with ESPTool methods """
 
     CHIP_TYPE_PATTERN = re.compile(r"Detecting chip type[.:\s]+(.+)")
+    # if need to erase NVS partition in start app
+    ERASE_NVS = True
 
     def __init__(self, name, port, log_file, app, **kwargs):
         self.download_config, self.partition_table = app.process_app_info()
@@ -68,24 +74,39 @@ class IDFDUT(DUT.SerialDUT):
         return cls.get_chip(app, port) is not None
 
     @_tool_method
-    def start_app(self):
+    def start_app(self, erase_nvs=ERASE_NVS):
         """
         download and start app.
 
+        :param: erase_nvs: whether erase NVS partition during flash
         :return: None
         """
+        if erase_nvs:
+            address = self.partition_table["nvs"]["offset"]
+            size = self.partition_table["nvs"]["size"]
+            nvs_file = tempfile.NamedTemporaryFile()
+            nvs_file.write(chr(0xFF) * size)
+            nvs_file.flush()
+            download_config = self.download_config + [address, nvs_file.name]
+        else:
+            download_config = self.download_config
+
         retry_baud_rates = ["921600", "115200"]
         error = IDFToolError()
-        for baud_rate in retry_baud_rates:
-            try:
-                subprocess.check_output(["python", self.app.esptool,
-                                         "--port", self.port, "--baud", baud_rate]
-                                        + self.download_config)
-                break
-            except subprocess.CalledProcessError as error:
-                continue
-        else:
-            raise error
+        try:
+            for baud_rate in retry_baud_rates:
+                try:
+                    subprocess.check_output(["python", self.app.esptool,
+                                             "--port", self.port, "--baud", baud_rate]
+                                            + download_config)
+                    break
+                except subprocess.CalledProcessError as error:
+                    continue
+            else:
+                raise error
+        finally:
+            if erase_nvs:
+                nvs_file.close()
 
     @_tool_method
     def reset(self):
@@ -96,6 +117,17 @@ class IDFDUT(DUT.SerialDUT):
         """
         subprocess.check_output(["python", self.app.esptool, "--port", self.port, "run"])
 
+    @_tool_method
+    def erase_partition(self, partition):
+        """
+        :param partition: partition name to erase
+        :return: None
+        """
+        address = self.partition_table[partition]["offset"]
+        size = self.partition_table[partition]["size"]
+        with open(".erase_partition.tmp", "wb") as f:
+            f.write(chr(0xFF) * size)
+
     @_tool_method
     def dump_flush(self, output_file, **kwargs):
         """