Extract default relay host test

centralize common test variables and functions

test/test_helper/common.bash

@@ -0,0 +1,35 @@
+load 'test_helper/bats-support/load'
+load 'test_helper/bats-assert/load'
+
+NAME=tvial/docker-mailserver:testing
+
+# default timeout is 60 seconds
+TEST_TIMEOUT_IN_SECONDS=${TIMEOUT-60}
+
+function repeat_until_success_or_timeout {
+    if ![[ "$1" ~= '^[0-9]+$' ]]; then
+        echo "First parameter for timeout must be an integer, recieved \"$1\""
+        exit 1
+    fi
+    TIMEOUT=$1
+    STARTTIME=$SECONDS
+    shift 1
+    until "$@"
+    do
+        sleep 5
+        if [[ $(($SECONDS - $STARTTIME )) -gt $TIMEOUT ]]; then
+            echo "Timed out on command: $@"
+            exit 1
+        fi
+    done
+}
+
+# @param $1 name of the postfix container
+function wait_for_smtp_port_in_container() {
+    repeat_until_success_or_timeout $TEST_TIMEOUT_IN_SECONDS docker exec $1 /bin/sh -c "nc -z 0.0.0.0 25"
+}
+
+# @param $1 name of the postfix container
+function wait_for_finished_setup_in_container() {
+    repeat_until_success_or_timeout $TEST_TIMEOUT_IN_SECONDS sh -c "docker logs $1 | grep 'Starting mail server'"
+}