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