printer YANG FEATURE initial implementation of YANG printer
diff --git a/tests/src/test_printer_yang.c b/tests/src/test_printer_yang.c
new file mode 100644
index 0000000..922b170
--- /dev/null
+++ b/tests/src/test_printer_yang.c
@@ -0,0 +1,202 @@
+/*
+ * @file test_printer_yang.c
+ * @author: Radek Krejci <rkrejci@cesnet.cz>
+ * @brief unit tests for functions from printer_yang.c
+ *
+ * Copyright (c) 2019 CESNET, z.s.p.o.
+ *
+ * This source code is licensed under BSD 3-Clause License (the "License").
+ * You may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://opensource.org/licenses/BSD-3-Clause
+ */
+
+#include "../../src/common.c"
+#include "../../src/set.c"
+#include "../../src/log.c"
+#include "../../src/hash_table.c"
+#include "../../src/xpath.c"
+#include "../../src/parser_yang.c"
+#include "../../src/context.c"
+#include "../../src/tree_schema_helpers.c"
+#include "../../src/tree_schema_free.c"
+#include "../../src/tree_schema_compile.c"
+#include "../../src/tree_schema.c"
+#include "../../src/printer_yang.c"
+#include "../../src/printer.c"
+
+#include <stdarg.h>
+#include <stddef.h>
+#include <setjmp.h>
+#include <cmocka.h>
+
+#include <stdio.h>
+#include <string.h>
+
+#include "libyang.h"
+
+#define BUFSIZE 1024
+char logbuf[BUFSIZE] = {0};
+int store = -1; /* negative for infinite logging, positive for limited logging */
+
+/* set to 0 to printing error messages to stderr instead of checking them in code */
+#define ENABLE_LOGGER_CHECKING 1
+
+#if ENABLE_LOGGER_CHECKING
+static void
+logger(LY_LOG_LEVEL level, const char *msg, const char *path)
+{
+    (void) level; /* unused */
+    if (store) {
+        if (path && path[0]) {
+            snprintf(logbuf, BUFSIZE - 1, "%s %s", msg, path);
+        } else {
+            strncpy(logbuf, msg, BUFSIZE - 1);
+        }
+        if (store > 0) {
+            --store;
+        }
+    }
+}
+#endif
+
+static int
+logger_setup(void **state)
+{
+    (void) state; /* unused */
+#if ENABLE_LOGGER_CHECKING
+    ly_set_log_clb(logger, 1);
+#endif
+    return 0;
+}
+
+static int
+logger_teardown(void **state)
+{
+    (void) state; /* unused */
+#if ENABLE_LOGGER_CHECKING
+    if (*state) {
+        fprintf(stderr, "%s\n", logbuf);
+    }
+#endif
+    return 0;
+}
+
+void
+logbuf_clean(void)
+{
+    logbuf[0] = '\0';
+}
+
+#if ENABLE_LOGGER_CHECKING
+#   define logbuf_assert(str) assert_string_equal(logbuf, str)
+#else
+#   define logbuf_assert(str)
+#endif
+
+
+static void
+test_module(void **state)
+{
+    *state = test_module;
+
+    struct ly_ctx *ctx = {0};
+    const struct lys_module *mod;
+    const char *orig = "module a {\n"
+            "  yang-version 1.1;\n"
+            "  namespace \"urn:test:a\";\n"
+            "  prefix a;\n\n"
+            "  import ietf-yang-types {\n"
+            "    prefix yt;\n"
+            "    revision-date 2013-07-15;\n"
+            "    description\n"
+            "      \"YANG types\";\n"
+            "    reference\n"
+            "      \"RFC reference\";\n"
+            "  }\n\n"
+            "  organization\n"
+            "    \"ORG\";\n"
+            "  contact\n"
+            "    \"Radek Krejci.\";\n"
+            "  description\n"
+            "    \"Long multiline\n"
+            "      description.\";\n"
+            "  reference\n"
+            "    \"some reference\";\n"
+            "}\n";
+    char *printed;
+
+    assert_int_equal(LY_SUCCESS, ly_ctx_new(NULL, 0, &ctx));
+
+    assert_non_null(mod = lys_parse_mem(ctx, orig, LYS_IN_YANG));
+    assert_int_equal(LY_SUCCESS, lys_print_mem(&printed, mod, LYS_OUT_YANG, 0, 0));
+    assert_string_equal(printed, orig);
+    free(printed);
+
+    orig = "module b {\n"
+            "  yang-version 1.1;\n"
+            "  namespace \"urn:test:b\";\n"
+            "  prefix b;\n\n"
+            "  revision 2019-04-16 {\n"
+            "    description\n"
+            "      \"text\";\n"
+            "    reference\n"
+            "      \"text\";\n"
+            "  }\n"
+            "  revision 2019-04-15 {\n"
+            "    description\n"
+            "      \"initial revision\";\n"
+            "  }\n\n"
+            "  feature f1 {\n"
+            "    status current;\n"
+            "    description\n"
+            "      \"text\";\n"
+            "    reference\n"
+            "      \"text\";\n"
+            "  }\n\n"
+            "  feature f2 {\n"
+            "    if-feature \"not f1\";\n"
+            "  }\n"
+            "}\n";
+    assert_non_null(mod = lys_parse_mem(ctx, orig, LYS_IN_YANG));
+    assert_int_equal(LY_SUCCESS, lys_print_mem(&printed, mod, LYS_OUT_YANG, 0, 0));
+    assert_string_equal(printed, orig);
+    free(printed);
+
+    orig = "module c {\n"
+            "  yang-version 1.1;\n"
+            "  namespace \"urn:test:c\";\n"
+            "  prefix c;\n\n"
+            "  feature f1;\n\n"
+            "  identity i1 {\n"
+            "    if-feature \"f1\";\n"
+            "    description\n"
+            "      \"text\";\n"
+            "    reference\n"
+            "      \"text32\";\n"
+            "  }\n\n"
+            "  identity i2 {\n"
+            "    base i1;\n"
+            "    status obsolete;\n"
+            "  }\n"
+            "}\n";
+    assert_non_null(mod = lys_parse_mem(ctx, orig, LYS_IN_YANG));
+    assert_int_equal(LY_SUCCESS, lys_print_mem(&printed, mod, LYS_OUT_YANG, 0, 0));
+    assert_string_equal(printed, orig);
+    free(printed);
+
+    *state = NULL;
+    ly_ctx_destroy(ctx, NULL);
+}
+
+/* TODO: include */
+
+int main(void)
+{
+    const struct CMUnitTest tests[] = {
+        cmocka_unit_test_setup_teardown(test_module, logger_setup, logger_teardown),
+    };
+
+    return cmocka_run_group_tests(tests, NULL, NULL);
+}