feat(python): use DebugLinkRecordScreen.refresh_index when restarting emulator

During each restart, Emulator will transfer the original screen-recording directory
to the new emulator/client and will change the refresh_index so that older screenshots
are not being overwritten by new ones.

[no changelog]

python/src/trezorlib/_internal/emulator.py

@@ -82,6 +82,9 @@ class Emulator:
         self.auto_interact = auto_interact
         self.extra_args = list(extra_args)
 
+        # To save all screenshots properly in one directory between restarts
+        self.restart_amount = 0
+
     @property
     def client(self) -> TrezorClientDebugLink:
         """So that type-checkers do not see `client` as `Optional`.
@@ -112,7 +115,7 @@ class Emulator:
                 if transport._ping():
                     break
                 if self.process.poll() is not None:
-                    raise RuntimeError("Emulator proces died")
+                    raise RuntimeError("Emulator process died")
 
                 elapsed = time.monotonic() - start
                 if elapsed >= timeout:
@@ -200,8 +203,15 @@ class Emulator:
         self.process = None
 
     def restart(self) -> None:
+        # preserving the recording directory between restarts
+        self.restart_amount += 1
+        prev_screenshot_dir = self.client.debug.screenshot_recording_dir
         self.stop()
         self.start()
+        if prev_screenshot_dir:
+            self.client.debug.start_recording(
+                prev_screenshot_dir, refresh_index=self.restart_amount
+            )
 
     def __enter__(self) -> "Emulator":
         return self

python/src/trezorlib/debuglink.py

@@ -195,6 +195,9 @@ class DebugLink:
         # To be set by TrezorClientDebugLink (is not known during creation time)
         self.model: Optional[str] = None
 
+        # Where screenshots are being saved
+        self.screenshot_recording_dir: Optional[str] = None
+
         # For T1 screenshotting functionality in DebugUI
         self.t1_take_screenshots = False
         self.t1_screenshot_directory: Optional[Path] = None
@@ -411,16 +414,24 @@ class DebugLink:
     def reseed(self, value: int) -> protobuf.MessageType:
         return self._call(messages.DebugLinkReseedRandom(value=value))
 
-    def start_recording(self, directory: str) -> None:
+    def start_recording(
+        self, directory: str, refresh_index: Optional[int] = None
+    ) -> None:
+        self.screenshot_recording_dir = directory
         # Different recording logic between TT and T1
         if self.model == "T":
-            self._call(messages.DebugLinkRecordScreen(target_directory=directory))
+            self._call(
+                messages.DebugLinkRecordScreen(
+                    target_directory=directory, refresh_index=refresh_index
+                )
+            )
         else:
             self.t1_screenshot_directory = Path(directory)
             self.t1_screenshot_counter = 0
             self.t1_take_screenshots = True
 
     def stop_recording(self) -> None:
+        self.screenshot_recording_dir = None
         # Different recording logic between TT and T1
         if self.model == "T":
             self._call(messages.DebugLinkRecordScreen(target_directory=None))