core: improve emulator wrapper

* supply a gzipped image of an empty SD card so that we don't spend 5s at
  every run by formatting it
* add start, stop, restart methods for direct control
* add restart capability to device_handler (a little awkward for now)

tests/device_handler.py

@@ -45,6 +45,13 @@ class BackgroundDeviceHandler:
                 pass
         self.task = None
 
+    def restart(self, emulator):
+        # TODO handle actual restart as well
+        self.kill_task()
+        emulator.restart()
+        self.client = emulator.client
+        self.client.ui = NullUI
+
     def result(self):
         if self.task is None:
             raise RuntimeError("No task running")

tests/emulators.py

@@ -14,6 +14,7 @@
 # You should have received a copy of the License along with this library.
 # If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.
 
+import gzip
 import os
 import subprocess
 import tempfile
@@ -21,15 +22,17 @@ import time
 from collections import defaultdict
 
 from trezorlib.debuglink import TrezorClientDebugLink
-from trezorlib.transport import TransportException, get_transport
+from trezorlib.transport.udp import UdpTransport
 
-BINDIR = os.path.dirname(os.path.abspath(__file__)) + "/emulators"
-ROOT = os.path.dirname(os.path.abspath(__file__)) + "/../"
+ROOT = os.path.abspath(os.path.dirname(__file__) + "/..")
+BINDIR = ROOT + "/tests/emulators"
 LOCAL_BUILD_PATHS = {
-    "core": ROOT + "core/build/unix/micropython",
-    "legacy": ROOT + "legacy/firmware/trezor.elf",
+    "core": ROOT + "/core/build/unix/micropython",
+    "legacy": ROOT + "/legacy/firmware/trezor.elf",
 }
 
+SD_CARD_GZ = ROOT + "/tests/trezor.sdcard.gz"
+
 ENV = {"SDL_VIDEODRIVER": "dummy"}
 
 
@@ -84,46 +87,68 @@ class EmulatorWrapper:
         if storage:
             open(self._storage_file(), "wb").write(storage)
 
+        with gzip.open(SD_CARD_GZ, "rb") as gz:
+            with open(self.workdir.name + "/trezor.sdcard", "wb") as sd:
+                sd.write(gz.read())
+
         self.client = None
 
-    def __enter__(self):
+    def _get_params_core(self):
+        env = ENV.copy()
+        args = [self.executable, "-m", "main"]
+        # for firmware 2.1.2 and newer
+        env["TREZOR_PROFILE_DIR"] = self.workdir.name
+        # for firmware 2.1.1 and older
+        env["TREZOR_PROFILE"] = self.workdir.name
+
+        if self.executable == LOCAL_BUILD_PATHS["core"]:
+            cwd = ROOT + "/core/src"
+        else:
+            cwd = self.workdir.name
+
+        return env, args, cwd
+
+    def _get_params_legacy(self):
+        env = ENV.copy()
         args = [self.executable]
-        env = ENV
+        cwd = self.workdir.name
+        return env, args, cwd
+
+    def _get_params(self):
         if self.gen == "core":
-            args += ["-m", "main"]
-            # for firmware 2.1.2 and newer
-            env["TREZOR_PROFILE_DIR"] = self.workdir.name
-            # for firmware 2.1.1 and older
-            env["TREZOR_PROFILE"] = self.workdir.name
+            return self._get_params_core()
+        elif self.gen == "legacy":
+            return self._get_params_legacy()
+        else:
+            raise ValueError("Unknown gen")
+
+    def start(self):
+        env, args, cwd = self._get_params()
         self.process = subprocess.Popen(
-            args, cwd=self.workdir.name, env=env, stdout=open(os.devnull, "w")
+            args, cwd=cwd, env=env, stdout=open(os.devnull, "w")
         )
+
         # wait until emulator is listening
+        transport = UdpTransport("127.0.0.1:21324")
+        transport.open()
         for _ in range(300):
-            try:
-                time.sleep(0.1)
-                transport = get_transport("udp:127.0.0.1:21324")
+            if transport._ping():
                 break
-            except TransportException:
-                pass
             if self.process.poll() is not None:
                 self._cleanup()
                 raise RuntimeError("Emulator proces died")
+            time.sleep(0.1)
         else:
             # could not connect after 300 attempts * 0.1s = 30s of waiting
             self._cleanup()
             raise RuntimeError("Can't connect to emulator")
+        transport.close()
 
         self.client = TrezorClientDebugLink(transport)
         self.client.open()
         check_version(self.tag, self.client.version)
-        return self
 
-    def __exit__(self, exc_type, exc_value, traceback):
-        self._cleanup()
-        return False
-
-    def _cleanup(self):
+    def stop(self):
         if self.client:
             self.client.close()
         self.process.terminate()
@@ -131,6 +156,20 @@ class EmulatorWrapper:
             self.process.wait(1)
         except subprocess.TimeoutExpired:
             self.process.kill()
+
+    def restart(self):
+        self.stop()
+        self.start()
+
+    def __enter__(self):
+        self.start()
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self._cleanup()
+
+    def _cleanup(self):
+        self.stop()
         self.workdir.cleanup()
 
     def _storage_file(self):