Add tests for every implemented command

tests/service_export.bats

@@ -0,0 +1,30 @@
+#!/usr/bin/env bats
+load test_helper
+
+setup() {
+  export ECHO_DOCKER_COMMAND="false"
+  dokku "$PLUGIN_COMMAND_PREFIX:create" l >&2
+}
+
+teardown() {
+  export ECHO_DOCKER_COMMAND="false"
+  dokku --force "$PLUGIN_COMMAND_PREFIX:destroy" l >&2
+}
+
+@test "($PLUGIN_COMMAND_PREFIX:export) error when there are no arguments" {
+  run dokku "$PLUGIN_COMMAND_PREFIX:export"
+  assert_contains "${lines[*]}" "Please specify a name for the service"
+}
+
+@test "($PLUGIN_COMMAND_PREFIX:export) error when service does not exist" {
+  run dokku "$PLUGIN_COMMAND_PREFIX:export" not_existing_service
+  assert_contains "${lines[*]}" "service not_existing_service does not exist"
+}
+
+@test "($PLUGIN_COMMAND_PREFIX:export) success" {
+  export ECHO_DOCKER_COMMAND="true"
+  run dokku "$PLUGIN_COMMAND_PREFIX:export" l
+  password="$(cat "$PLUGIN_DATA_ROOT/l/PASSWORD")"
+  assert_output "docker exec dokku.postgres.l env PGPASSWORD=$password pg_dump -Fc --no-acl --no-owner -h localhost -U postgres -w l"
+}
+