test(p6-protocol): unit + integration coverage for --protocol

tests/integration/test_preflight.py

@@ -2,10 +2,11 @@
 import subprocess
 import sys
 import os
+import shutil
 import pytest
 
 sys.path.insert(0, os.path.dirname(__file__))
-from common import BUILD_DIR, CLIENT_CMD, SERVER_CMD
+from common import BUILD_DIR, CLIENT_CMD, SERVER_CMD, TEST_DATA_DIR, run_client, verify_transfer
 
 
 class TestHelp:
@@ -79,3 +80,58 @@ class TestServerPort:
         finally:
             proc.terminate()
             proc.wait(timeout=5)
+
+
+def _seed_protocol_source(source):
+    os.makedirs(source, exist_ok=True)
+    with open(os.path.join(source, "p.txt"), "w") as fh:
+        fh.write("protocol test\n")
+    os.makedirs(os.path.join(source, "nested"), exist_ok=True)
+    with open(os.path.join(source, "nested", "deep.txt"), "w") as fh:
+        fh.write("deep file\n")
+
+
+class TestProtocol:
+    @pytest.mark.ci
+    def test_protocol_current_version_accepted(self, shared_server):
+        """--protocol=2.16.0 (the current PROTOCOL_VERSION) is accepted and the
+        transfer completes normally."""
+        source = os.path.join(TEST_DATA_DIR, "proto_ok_src")
+        dest = os.path.join(TEST_DATA_DIR, "proto_ok_dst")
+        shutil.rmtree(dest, ignore_errors=True)
+        os.makedirs(dest)
+        _seed_protocol_source(source)
+        result, _ = run_client(source, dest, flags=["--protocol=2.16.0"],
+                               port=shared_server.port)
+        assert result.returncode == 0, \
+            f"--protocol current run failed: {(result.stderr or result.stdout)[:400]}"
+        received = os.path.join(dest, os.path.abspath(source).lstrip(os.sep))
+        mismatches, missing = verify_transfer(source, received)
+        assert not mismatches and not missing, \
+            f"transfer mismatch: missing={missing} mismatches={mismatches}"
+
+    @pytest.mark.ci
+    def test_protocol_rejects_other_versions(self, shared_server):
+        """Other versions are rejected up front, before connecting."""
+        source = os.path.join(TEST_DATA_DIR, "proto_reject_src")
+        dest = os.path.join(TEST_DATA_DIR, "proto_reject_dst")
+        shutil.rmtree(dest, ignore_errors=True)
+        os.makedirs(dest)
+        _seed_protocol_source(source)
+        for bad in ("2.15.0", "2.17.0", "216", "31"):
+            result, _ = run_client(source, dest, flags=[f"--protocol={bad}"],
+                                   port=shared_server.port)
+            assert result.returncode != 0, f"--protocol={bad} should be rejected"
+
+    @pytest.mark.ci
+    def test_protocol_rejects_garbage(self, shared_server):
+        """Garbage/empty --protocol values are rejected up front."""
+        source = os.path.join(TEST_DATA_DIR, "proto_garbage_src")
+        dest = os.path.join(TEST_DATA_DIR, "proto_garbage_dst")
+        shutil.rmtree(dest, ignore_errors=True)
+        os.makedirs(dest)
+        _seed_protocol_source(source)
+        for bad in ("abc", ""):
+            result, _ = run_client(source, dest, flags=[f"--protocol={bad}"],
+                                   port=shared_server.port)
+            assert result.returncode != 0, f"--protocol={bad} should be rejected"

tests/test_client_cli.c

@@ -210,6 +210,66 @@ static void test_parse_args_version() {
   config_delete(cfg);
 }
 
+/* --protocol=NUM forces the wire protocol version: the current PROTOCOL_VERSION
+ * is accepted (stored into config->version, which the config frame transmits),
+ * and any other value is rejected.  Client-only: no server-side flag exists. */
+static void test_parse_args_protocol_accept_current() {
+  Config* cfg = valid_client_config();
+  EXPECT_NOT_NULL(cfg);
+  char* argv_equals[] = {"fastsync",   "--source-dir", "/src",
+                         "--dest-dir", "/dst",         "--protocol=2.16.0"};
+  int positional_args[2];
+  int positional_count = 0;
+  EXPECT_EQ_INT(parse_args(cfg, 6, argv_equals, positional_args, &positional_count), 0);
+  EXPECT_EQ_STR(cfg->version, PROTOCOL_VERSION);
+  config_delete(cfg);
+
+  cfg = valid_client_config();
+  EXPECT_NOT_NULL(cfg);
+  char* argv_space[] = {"fastsync", "--source-dir", "/src",  "--dest-dir",
+                        "/dst",     "--protocol",   "2.16.0"};
+  positional_count = 0;
+  EXPECT_EQ_INT(parse_args(cfg, 7, argv_space, positional_args, &positional_count), 0);
+  EXPECT_EQ_STR(cfg->version, PROTOCOL_VERSION);
+  config_delete(cfg);
+}
+
+/* Any --protocol value other than the current PROTOCOL_VERSION must end in
+ * failure (parse_args simply stores it; validate_config rejects it up front). */
+static void test_parse_args_protocol_rejects_other_versions() {
+  static const char* const bad_versions[] = {"2.16", "2.15.0", "2.17.0", "216", "31", "abc", ""};
+  for (size_t i = 0; i < sizeof(bad_versions) / sizeof(bad_versions[0]); i++) {
+    Config* cfg = valid_client_config();
+    EXPECT_NOT_NULL(cfg);
+    char arg[64];
+    snprintf(arg, sizeof(arg), "--protocol=%s", bad_versions[i]);
+    char* argv[] = {"fastsync", "--source-dir", "/src", "--dest-dir", "/dst", arg};
+    int positional_args[2];
+    int positional_count = 0;
+    EXPECT_EQ_INT(parse_args(cfg, 6, argv, positional_args, &positional_count), 0);
+    EXPECT_TRUE(strcmp(cfg->version, PROTOCOL_VERSION) != 0);
+    EXPECT_FALSE(validate_config(cfg));
+    config_delete(cfg);
+  }
+}
+
+/* validate_config accepts the current PROTOCOL_VERSION (the default) and rejects
+ * a version that does not equal it -- the honest post-parse enforcement. */
+static void test_validate_config_protocol_version() {
+  Config* cfg = valid_client_config();
+  EXPECT_NOT_NULL(cfg);
+  EXPECT_EQ_STR(cfg->version, PROTOCOL_VERSION);
+  EXPECT_TRUE(validate_config(cfg));
+  config_delete(cfg);
+
+  cfg = valid_client_config();
+  EXPECT_NOT_NULL(cfg);
+  free(cfg->version);
+  cfg->version = str_dup("2.15.0");
+  EXPECT_FALSE(validate_config(cfg));
+  config_delete(cfg);
+}
+
 /* --xattrs/-X and --acls/-A preserve per-file xattrs and both imply metadata
  * transmission (the xattr block rides the metadata/per-file frame); each is
  * individually negatable and the derived use_xattrs follows the flags. */
@@ -2850,6 +2910,9 @@ void test_client_cli() {
   test_cli_exclude_patterns();
   test_parse_args_help();
   test_parse_args_version();
+  test_parse_args_protocol_accept_current();
+  test_parse_args_protocol_rejects_other_versions();
+  test_validate_config_protocol_version();
   test_parse_args_valid_port();
   test_parse_args_size_only();
   test_parse_args_ignore_existing();