Make serde of google protobufs idempotent

src/proto_file.py

@@ -136,9 +136,9 @@ def construct(
     @staticmethod
     def parse_syntax_and_preceding_comments(
         proto_content: str,
-    ) -> tuple[ProtoSyntax, Sequence[ProtoComment], str]:
+    ) -> tuple[ProtoSyntax, Sequence[ProtoNode], str]:
         # First, parse any preceding comments.
-        parsed_tree = []
+        parsed_tree: list[ProtoNode] = []
         while True:
             for node_type in [ProtoSingleLineComment, ProtoMultiLineComment]:
                 try:
@@ -161,6 +161,7 @@ def parse_syntax_and_preceding_comments(
             raise ValueError(f"Proto doesn't have parseable syntax:\n{proto_content}")
         syntax = syntax_match.node
         proto_content = syntax_match.remaining_source.strip()
+        parsed_tree.append(syntax)
 
         return syntax, parsed_tree, proto_content
 
@@ -172,7 +173,7 @@ def normalize(self) -> Optional["ProtoNode"]:
         )
 
     def serialize(self) -> str:
-        serialized_parts = [self.syntax.serialize()]
+        serialized_parts = []
         previous_type: type[ProtoNode] = self.syntax.__class__
         for node in self.nodes:
             # Attempt to group up lines of the same type.

src/proto_syntax.py

@@ -21,7 +21,7 @@ def __init__(self, syntax: ProtoStringLiteral, *args, **kwargs):
         self.syntax = syntax
 
     def __eq__(self, other) -> bool:
-        return self.syntax == other.syntax
+        return isinstance(other, ProtoSyntax) and self.syntax == other.syntax
 
     def __str__(self) -> str:
         return f"<ProtoSyntax syntax={self.syntax.serialize()}>"

test/util/parser_binary_test.sh

@@ -1,16 +1,21 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
+function compare_proto() {
+    # Takes one argument, the relative path to the proto to compare.
+    echo $1
+    ./src/util/parser_binary $1 > "${1}_serialized.proto"
+    diff --side-by-side --ignore-all-space --ignore-blank-lines $1 "${1}_serialized.proto"
+}
+
 echo "Local protos:"
 LOCAL_PROTOS=$(find ./test/resources -name "*.proto" | sort)
 for f in $LOCAL_PROTOS; do
-    echo $f
-    ./src/util/parser_binary $f > /dev/null
+    compare_proto $f
 done
 
 echo "Google protos:"
 GOOGLE_PROTOS=$(find ./external/com_google_protobuf/src/google/protobuf -name "*.proto" | xargs grep --files-without-match "proto2" | sort)
 for f in $GOOGLE_PROTOS; do
-    echo $f
-    ./src/util/parser_binary $f > /dev/null
+    compare_proto $f
 done