add env var parsing to cli. Current tests pass but I need to add new ones

src/debugpy/server/cli.py

@@ -7,10 +7,7 @@ import os
 import re
 import sys
 from importlib.util import find_spec
-from typing import Any
-from typing import Union
-from typing import Tuple
-from typing import Dict
+from typing import Any, Union, Tuple, Dict
 
 # debugpy.__main__ should have preloaded pydevd properly before importing this module.
 # Otherwise, some stdlib modules above might have had imported threading before pydevd
@@ -193,48 +190,22 @@ switches = [
 ]
 # fmt: on
 
-
-def consume_argv():
-    while len(sys.argv) >= 2:
-        value = sys.argv[1]
-        del sys.argv[1]
+# Consume all the args from a given list
+def consume_args(args: list):
+    while len(args) >= 2:
+        value = args[1]
+        del args[1]
         yield value
 
+# Parse the args from the command line, then from the environment.
+# Args from the environment are only used if they are not already set from the command line.
+def parse_args():
 
-def parse_argv():
+    # keep track of the switches we've seen so far
     seen = set()
-    it = consume_argv()
 
-    while True:
-        try:
-            arg = next(it)
-        except StopIteration:
-            raise ValueError("missing target: " + TARGET)
-
-        switch = arg
-        if not switch.startswith("-"):
-            switch = ""
-        for pattern, placeholder, action in switches:
-            if re.match("^(" + pattern + ")$", switch):
-                break
-        else:
-            raise ValueError("unrecognized switch " + switch)
-
-        if switch in seen:
-            raise ValueError("duplicate switch " + switch)
-        else:
-            seen.add(switch)
-
-        try:
-            action(arg, it)
-        except StopIteration:
-            assert placeholder is not None
-            raise ValueError("{0}: missing {1}".format(switch, placeholder))
-        except Exception as exc:
-            raise ValueError("invalid {0} {1}: {2}".format(switch, placeholder, exc))
-
-        if options.target is not None:
-            break
+    parse_args_from_command_line(seen)
+    parse_args_from_environment(seen)
 
     if options.mode is None:
         raise ValueError("either --listen or --connect is required")
@@ -247,6 +218,75 @@ def parse_argv():
     assert options.target_kind is not None
     assert options.address is not None
 
+def parse_args_from_command_line(seen: set):
+    parse_args_helper(sys.argv, seen)
+
+def parse_args_from_environment(seenFromCommandLine: set):
+    args = os.getenv("DEBUGPY_EXTRA_ARGV")
+    if (not args):
+        return
+
+    argsList = args.split()
+    seenFromEnvironment = set()
+    parse_args_helper(argsList, seenFromCommandLine, seenFromEnvironment, True)
+
+def parse_args_helper(args: list, seenFromCommandLine: set, seenFromEnvironment: set = None, isFromEnvironment=False):
+    it = consume_args(args)
+
+    while True:
+        try:
+            arg = next(it)
+        except StopIteration:
+            # If we get here, we've processed all the arguments.
+
+            # If we're parsing from the command line, we should never get here, so this is an error
+            # (because we break from the loop as soon as the target is set).
+            if (not isFromEnvironment):
+                raise ValueError("missing target: " + TARGET)
+            # Otherwise, we're done parsing from the environment, so make sure the target is set
+            else:
+                if (options.target is None):
+                    raise ValueError("missing target from environment: " + TARGET)
+
+        switch = arg
+        if not switch.startswith("-"):
+            switch = ""
+        for pattern, placeholder, action in switches:
+            if re.match("^(" + pattern + ")$", switch):
+                break
+        else:
+            raise ValueError("unrecognized switch " + switch)
+
+        # if we're parsing from the command line, and we've already seen the switch on the command line, this is an error
+        if (not isFromEnvironment and switch in seenFromCommandLine):
+            raise ValueError("duplicate switch on command line" + switch)
+        # if we're parsing from the environment, and we've already seen the switch in the environment, this is an error
+        elif (isFromEnvironment and switch in seenFromEnvironment):
+            raise ValueError("duplicate switch from environment" + switch)
+        # if we're parsing from the environment, and we've already seen the switch on the command line, skip it, since command line takes precedence
+        elif (isFromEnvironment and switch in seenFromCommandLine):
+            continue
+        # otherwise, the switch is new, so add it to the appropriate set
+        else:
+            if (isFromEnvironment):
+                seenFromEnvironment.add(switch)
+            else:
+                seenFromCommandLine.add(switch)
+
+        # process the switch, running the corresponding action
+        try:
+            action(arg, it)
+        except StopIteration:
+            assert placeholder is not None
+            raise ValueError("{0}: missing {1}".format(switch, placeholder))
+        except Exception as exc:
+            raise ValueError("invalid {0} {1}: {2}".format(switch, placeholder, exc))
+
+        # If we're parsing the command line, we're done after we've processed the target
+        # Otherwise, we need to keep parsing until all args are consumed, since the target may be set from the command line
+        # already, but there might be additional args in the environment that we want to process.
+        if (not isFromEnvironment and options.target is not None):
+            break
 
 def start_debugging(argv_0):
     # We need to set up sys.argv[0] before invoking either listen() or connect(),
@@ -411,7 +451,7 @@ attach_pid_injected.attach(setup);
 def main():
     original_argv = list(sys.argv)
     try:
-        parse_argv()
+        parse_args()
     except Exception as exc:
         print(str(HELP) + str("\nError: ") + str(exc), file=sys.stderr)
         sys.exit(2)

tests/debugpy/server/test_cli.py

@@ -21,7 +21,7 @@ def cli(pyfile):
         from debugpy.server import cli
 
         try:
-            cli.parse_argv()
+            cli.parse_args()
         except Exception as exc:
             os.write(1, pickle.dumps(exc))
             sys.exit(1)