Catch FileNotFoundError exception

When we want to find some Postgres process in testgres psutils lib first gets list of all system processes (children() function in testgres's auxiliary_processes). Next testgres asks for process name (cmdline() function), so psutils goes to /proc/pid/ in Linux. In case any of processes listed in previous step, we get FileNotFoundError

Author: Sofia Kopikova

testgres/enums.py

@@ -68,11 +68,15 @@ def from_process(process):
             ],
         }  # yapf: disable
 
+        try:
+            cmdline = ''.join(process.cmdline())
+        except (FileNotFoundError, ProcessLookupError):
+            return ProcessType.Unknown
+
         # we deliberately cut special words and spaces
-        cmdline = ''.join(process.cmdline()) \
-                    .replace('postgres:', '', 1) \
-                    .replace('bgworker:', '', 1) \
-                    .replace(' ', '')
+        cmdline = cmdline.replace('postgres:', '', 1) \
+            .replace('bgworker:', '', 1) \
+            .replace(' ', '')
 
         for ptype in ProcessType:
             if cmdline.startswith(ptype.value.replace(' ', '')):