libpq_pipeline: Test the default protocol version

In preparation for a future change to libpq's default protocol version,
pin today's default (3.0) in the libpq_pipeline tests.

Patch by Jelte Fennema-Nio, with some additional refactoring of the
PQconnectdbParams() logic by me.

Author: Jelte Fennema-Nio <postgres@jeltef.nl>
Discussion: https://postgr.es/m/DDPR5BPWH1RJ.1LWAK6QAURVAY%40jeltef.nl

diff --git a/src/test/modules/libpq_pipeline/libpq_pipeline.c b/src/test/modules/libpq_pipeline/libpq_pipeline.c
index 03371721460cc9aa18a844848967047af29febde..0fb44be32ced4d5198a3b3bd41bac5fff4cff04a 100644 (file)
--- a/src/test/modules/libpq_pipeline/libpq_pipeline.c
+++ b/src/test/modules/libpq_pipeline/libpq_pipeline.c
@@ -1328,17 +1328,13 @@ test_protocol_version(PGconn *conn)
        int                     nopts;
        PQconninfoOption *opts = PQconninfo(conn);
        int                     protocol_version;
-       int                     max_protocol_version_index;
+       int                     max_protocol_version_index = -1;
        int                     i;
 
-       /*
-        * Prepare keywords/vals arrays, copied from the existing connection, with
-        * an extra slot for 'max_protocol_version'.
-        */
+       /* Prepare keywords/vals arrays, copied from the existing connection. */
        nopts = 0;
        for (PQconninfoOption *opt = opts; opt->keyword != NULL; ++opt)
                nopts++;
-       nopts++;                                        /* max_protocol_version */
        nopts++;                                        /* NULL terminator */
 
        keywords = pg_malloc0(sizeof(char *) * nopts);
@@ -1347,18 +1343,40 @@ test_protocol_version(PGconn *conn)
        i = 0;
        for (PQconninfoOption *opt = opts; opt->keyword != NULL; ++opt)
        {
-               if (opt->val)
-               {
-                       keywords[i] = opt->keyword;
-                       vals[i] = opt->val;
-                       i++;
-               }
+               /*
+                * If the test already specified max_protocol_version, we want to
+                * replace it rather than attempting to override it. This matters when
+                * testing defaults, because empty option values at the end of the
+                * connection string won't replace earlier settings.
+                */
+               if (strcmp(opt->keyword, "max_protocol_version") == 0)
+                       max_protocol_version_index = i;
+               else if (!opt->val)
+                       continue;
+
+               keywords[i] = opt->keyword;
+               vals[i] = opt->val;
+
+               i++;
        }
 
-       max_protocol_version_index = i;
-       keywords[i] = "max_protocol_version";   /* value is filled in below */
-       i++;
-       keywords[i] = vals[i] = NULL;
+       Assert(max_protocol_version_index >= 0);
+
+       /*
+        * Test default protocol_version
+        */
+       vals[max_protocol_version_index] = "";
+       conn = PQconnectdbParams(keywords, vals, false);
+
+       if (PQstatus(conn) != CONNECTION_OK)
+               pg_fatal("Connection to database failed: %s",
+                                PQerrorMessage(conn));
+
+       protocol_version = PQfullProtocolVersion(conn);
+       if (protocol_version != 30000)
+               pg_fatal("expected 30000, got %d", protocol_version);
+
+       PQfinish(conn);
 
        /*
         * Test max_protocol_version=3.0