tests: hold off until daemon is available

The postgresql container initializes DB files e.a. in these tests, this
can take a couple of seconds. Try contacting it for up to 20 seconds,
and only then run the tests: create a table, store something in it and
retrieve it again.

tests/config.yaml

@@ -43,11 +43,23 @@ test:
             done
             test "$up" -ne 0
 testhost:
-    selfcheck:
-        - 'env PGPASSWORD=mtftest psql -h localhost -U mtftest -f test.sql | egrep "anything|something"'
-        #- 'echo errr | nc localhost 11211'
-        #- 'echo set AAA 0 4 2 | nc localhost 11211'
-        #- 'echo get AAA | nc localhost 11211'
-    #selcheckError:
-        #- 'echo errr | nc localhost 11211 |grep ERROR'
-
+    db_usable:
+        - |
+            export PGPASSWORD=mtftest
+            PSQL="psql -h localhost -U mtftest -q"
+            up=0
+            for i in `seq 20`; do
+                echo "Pinging PostgreSQL ($i)"
+                if $PSQL -c "" >&/dev/null; then
+                    up=1
+                    break
+                else
+                    sleep 1
+                fi
+            done
+            if [ "$up" -eq 1 ]; then
+                $PSQL -f test.sql | egrep "anything|something"
+            else
+                echo "Unable to connect to database." >&2
+                false
+            fi