Do not overwrite process log file across test units (#105)

* do not overwrite process log files

* add changelog entry

* rollback server.py handler

* add changelog entry

* stop overwriting log files

* remove comment

Author: northernSage

CHANGELOG.rst

@@ -1,10 +1,15 @@
+0.21.0 (Unreleased)
+-------------------
+
+- Process log files will not be overwritten for each new process anymore, making it
+  easier to debug issues that occurred in the middle of failed test runs
+
 0.20.0 (2022-08-29)
 -------------------
 
-- cleanup reminders will now only be printed for verbosity
+- Cleanup reminders will now only be printed for verbosity
   levels equal or greater than 1
 
-
 0.19.0 (2022-05-23)
 -------------------
 

xprocess/pytest_xprocess.py

@@ -1,9 +1,21 @@
+import os
+
 import py
 import pytest
 
 from xprocess import XProcess
 
 
+def get_log_files(root_dir):
+    proc_dirs = [f.path for f in os.scandir(root_dir) if f.is_dir()]
+    return [
+        os.path.join(proc_dir, f)
+        for proc_dir in proc_dirs
+        for f in os.listdir(proc_dir)
+        if f.endswith("log")
+    ]
+
+
 def getrootdir(config):
     return config.cache.makedir(".xprocess")
 
@@ -42,6 +54,9 @@ def xprocess(request):
         # pass in xprocess object into pytest_unconfigure
         # through config for proper cleanup during teardown
         request.config._xprocess = xproc
+        # start every run with clean log files
+        for log_file in get_log_files(xproc.rootdir):
+            open(log_file, "w").close()
         yield xproc
 
 

xprocess/xprocess.py

@@ -13,6 +13,9 @@
 from py import std
 
 
+XPROCESS_BLOCK_DELIMITER = "@@__xproc_block_delimiter__@@"
+
+
 class XProcessInfo:
     """Holds information of an active process instance represented by
     a XProcess Object and offers recursive termination functionality of
@@ -81,7 +84,7 @@ def terminate(self, *, kill_proc_tree=True, timeout=20):
                 self._signal_process(p, signal.SIGTERM)
             _, alive = psutil.wait_procs(kill_list, timeout=timeout)
 
-            # forcefuly terminate procs still running
+            # forcefully terminate procs still running
             for p in alive:
                 self._signal_process(p, signal.SIGKILL)
             _, alive = psutil.wait_procs(kill_list, timeout=timeout)
@@ -229,7 +232,8 @@ def ensure(self, name, preparefunc, restart=False):
             starter = preparefunc(controldir, self)
             args = [str(x) for x in starter.args]
             self.log.debug("%s$ %s", controldir, " ".join(args))
-            stdout = open(str(info.logpath), "wb", 0)
+            stdout = open(str(info.logpath), "a+b", 0)
+            stdout.write(bytes(f"{XPROCESS_BLOCK_DELIMITER}\n", "utf8"))
 
             # is env still necessary? we could pass all in popen_kwargs
             kwargs = {"env": starter.env}
@@ -266,6 +270,18 @@ def ensure(self, name, preparefunc, restart=False):
         # cleanup later during teardown phase
         xresource.fhandle = info.logpath.open()
 
+        # skip previous process logs
+        lines = info.logpath.open().readlines()
+        if lines:
+            proc_block_counter = sum(
+                1 for line in lines if XPROCESS_BLOCK_DELIMITER in line
+            )
+            for line in xresource.fhandle:
+                if XPROCESS_BLOCK_DELIMITER in line:
+                    proc_block_counter -= 1
+                if proc_block_counter <= 0:
+                    break
+
         self.resources.append(xresource)
 
         if not restart: