test: stabilize proxy tests

tests/assertions.py

@@ -666,18 +666,23 @@ def assert_failed_proxy_auth_request(stdout):
     )
 
 
-def wait_for_file(path, timeout=10.0, poll_interval=0.1):
-    import glob
+def wait_for(condition, timeout=10.0, interval=0.1):
     import time
 
     deadline = time.time() + timeout
     while time.time() < deadline:
-        if glob.glob(str(path)):
+        if condition():
             return True
-        time.sleep(poll_interval)
+        time.sleep(interval)
     return False
 
 
+def wait_for_file(path, timeout=10.0, interval=0.1):
+    import glob
+
+    return wait_for(lambda: glob.glob(str(path)), timeout, interval)
+
+
 def wait_for_daemon(tmp_path, started_at, timeout=None):
     import time
 
@@ -704,3 +709,36 @@ def wait_for_daemon(tmp_path, started_at, timeout=None):
         time.sleep(0.1)
 
     return False
+
+
+def wait_for_stdout(process, predicate, timeout=10):
+    """Read a process's stdout in a background thread, polling until
+    *predicate(text)* is satisfied or *timeout* expires.
+
+    Returns the full stdout text collected up to that point.
+    The caller should terminate/kill the process after this returns
+    to close the pipe and let the background thread exit.
+    """
+    import threading
+
+    lines = []
+
+    def reader():
+        try:
+            for line in iter(process.stdout.readline, b""):
+                lines.append(line)
+        except ValueError:
+            pass
+
+    thread = threading.Thread(target=reader, daemon=True)
+    thread.start()
+
+    def stdout_text():
+        return b"".join(lines).decode("utf-8", errors="replace")
+
+    if not wait_for(lambda: predicate(stdout_text()), timeout):
+        raise TimeoutError(
+            f"Predicate not satisfied within {timeout}s.\n"
+            f"Collected output:\n{stdout_text()}"
+        )
+    return stdout_text()

tests/proxy.py

@@ -8,7 +8,7 @@
 
 import pytest
 
-from tests.assertions import assert_no_proxy_request
+from tests.assertions import assert_no_proxy_request, wait_for, wait_for_stdout
 
 
 @contextlib.contextmanager
@@ -98,8 +98,14 @@ def start_mitmdump(
         if proxy_auth:
             proxy_command += ["-v", "--proxyauth", proxy_auth]
 
+        proxy_env = os.environ.copy()
+        proxy_env["PYTHONUNBUFFERED"] = "1"
+
         proxy_process = subprocess.Popen(
-            proxy_command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT
+            proxy_command,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.STDOUT,
+            env=proxy_env,
         )
 
         try:
@@ -126,20 +132,32 @@ def proxy_test_finally(
     proxy_process,
     proxy_log_assert=assert_no_proxy_request,
     expected_proxy_logsize=None,
+    timeout=10,
 ):
     if expected_proxy_logsize is None:
         expected_proxy_logsize = expected_httpserver_logsize
 
     if proxy_process:
-        # Give mitmdump some time to get a response from the mock server
-        time.sleep(0.5)
-        proxy_process.terminate()
-        stdout_bytes, _ = proxy_process.communicate()
-        stdout = stdout_bytes.decode("utf-8", errors="replace")
+        try:
+            # Give mitmdump some time to get a response from the mock server
+            assert wait_for(
+                lambda: len(httpserver.log) >= expected_httpserver_logsize, timeout
+            )
+
+            if expected_proxy_logsize != 0:
+                # request passed through successfully
+                wait_for_stdout(
+                    proxy_process,
+                    lambda text: "POST" in text and "200 OK" in text,
+                    timeout,
+                )
+        finally:
+            proxy_process.terminate()
+            proxy_process.wait(timeout=timeout)
+
         if expected_proxy_logsize == 0:
             # don't expect any incoming requests to make it through the proxy
+            stdout_bytes, _ = proxy_process.communicate(timeout=timeout)
+            stdout = stdout_bytes.decode("utf-8", errors="replace")
             proxy_log_assert(stdout)
-        else:
-            # request passed through successfully
-            assert "POST" in stdout and "200 OK" in stdout
     assert len(httpserver.log) == expected_httpserver_logsize

tests/test_dotnet_signals.py

@@ -8,6 +8,7 @@
 import pytest
 
 from tests import adb
+from tests.assertions import wait_for
 from tests.conditions import is_android, is_arm32, is_tsan, is_x86, is_asan
 
 project_fixture_path = pathlib.Path("tests/fixtures/dotnet_signal")
@@ -281,15 +282,6 @@ def test_aot_signals_inproc(cmake):
 ANDROID_PACKAGE = "io.sentry.ndk.dotnet.signal.test"
 
 
-def wait_for(condition, timeout=10, interval=0.5):
-    start = time.time()
-    while time.time() - start < timeout:
-        if condition():
-            return True
-        time.sleep(interval)
-    return condition()
-
-
 def run_android(args=None, strategy=None, reinit=False, timeout=30):
     if args is None:
         args = []