make_grpcio_tools.py improvements: more readable diffs (#32583)

- sort source files to ensure stable ordering
- generate one source file per line

together this should produce diffs that are much more readable by humans
when sources get added/removed to/from protobuf (and
make_grpcio_tools.py is used to regenerate).

tools/distrib/python/make_grpcio_tools.py

@@ -21,6 +21,7 @@ import filecmp
 import glob
 import os
 import os.path
+import pprint
 import shutil
 import subprocess
 import sys
@@ -44,6 +45,7 @@ DEPS_FILE_CONTENT = """
 
 # AUTO-GENERATED BY make_grpcio_tools.py!
 CC_FILES={cc_files}
+
 PROTO_FILES={proto_files}
 
 CC_INCLUDE={cc_include}
@@ -106,6 +108,18 @@ def bazel_query(query):
     return output.decode("ascii").splitlines()
 
 
+def _pretty_print_list(items):
+    """Pretty print python list"""
+    formatted = pprint.pformat(items, indent=4)
+    # add newline after opening bracket (and fix indent of the next line)
+    if formatted.startswith('['):
+        formatted = formatted[0] + '\n ' + formatted[1:]
+    # add newline before closing bracket
+    if formatted.endswith(']'):
+        formatted = formatted[:-1] + '\n' + formatted[-1]
+    return formatted
+
+
 def get_deps():
     """Write the result of the bazel query `query` against protobuf to
      `out_file`."""
@@ -125,8 +139,8 @@ def get_deps():
     ]
     commit_hash = protobuf_submodule_commit_hash()
     deps_file_content = DEPS_FILE_CONTENT.format(
-        cc_files=cc_files,
-        proto_files=proto_files,
+        cc_files=_pretty_print_list(sorted(cc_files)),
+        proto_files=_pretty_print_list(sorted(proto_files)),
         cc_include=repr(GRPC_PYTHON_PROTOBUF_RELATIVE_ROOT),
         proto_include=repr(GRPC_PYTHON_PROTOBUF_RELATIVE_ROOT),
         commit_hash=COMMIT_HASH_PREFIX + commit_hash + COMMIT_HASH_SUFFIX)