move interop tests tools into tests folder

tests/utils/interop/process.py

@@ -0,0 +1,72 @@
+from abc import (
+    ABC,
+    abstractmethod,
+)
+import subprocess
+from typing import (
+    Iterable,
+    List,
+)
+
+import trio
+
+TIMEOUT_DURATION = 30
+
+
+class AbstractInterativeProcess(ABC):
+    @abstractmethod
+    async def start(self) -> None:
+        ...
+
+    @abstractmethod
+    async def close(self) -> None:
+        ...
+
+
+class BaseInteractiveProcess(AbstractInterativeProcess):
+    proc: trio.Process = None
+    cmd: str
+    args: List[str]
+    bytes_read: bytearray
+    patterns: Iterable[bytes] = None
+    event_ready: trio.Event
+
+    async def wait_until_ready(self) -> None:
+        patterns_occurred = {pat: False for pat in self.patterns}
+
+        async def read_from_daemon_and_check() -> None:
+            async for data in self.proc.stdout:
+                # TODO: It takes O(n^2), which is quite bad.
+                # But it should succeed in a few seconds.
+                self.bytes_read.extend(data)
+                for pat, occurred in patterns_occurred.items():
+                    if occurred:
+                        continue
+                    if pat in self.bytes_read:
+                        patterns_occurred[pat] = True
+                if all([value for value in patterns_occurred.values()]):
+                    return
+
+        with trio.fail_after(TIMEOUT_DURATION):
+            await read_from_daemon_and_check()
+        self.event_ready.set()
+        # Sleep a little bit to ensure the listener is up after logs are emitted.
+        await trio.sleep(0.01)
+
+    async def start(self) -> None:
+        if self.proc is not None:
+            return
+        # mypy says that `open_process` is not an attribute of trio, suggests run_process instead.  # noqa: E501
+        self.proc = await trio.open_process(  # type: ignore[attr-defined]
+            [self.cmd] + self.args,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.STDOUT,  # Redirect stderr to stdout, which makes parsing easier  # noqa: E501
+            bufsize=0,
+        )
+        await self.wait_until_ready()
+
+    async def close(self) -> None:
+        if self.proc is None:
+            return
+        self.proc.terminate()
+        await self.proc.wait()