diff --git a/tests/features/test_metadata.c b/tests/features/test_metadata.c
new file mode 100644
index 0000000..9c60e37
--- /dev/null
+++ b/tests/features/test_metadata.c
@@ -0,0 +1,186 @@
+/*
+ * @file test_metadata.c
+ * @author: Radek Krejci <rkrejci@cesnet.cz>
+ * @brief unit tests for Metadata extension (annotation) support
+ *
+ * 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 "tests/config.h"
+
+#include <stdarg.h>
+#include <stddef.h>
+#include <setjmp.h>
+#include <cmocka.h>
+
+#include <stdio.h>
+#include <string.h>
+
+#include "../../src/libyang.h"
+#include "../../src/plugins_exts_metadata.h"
+
+#define BUFSIZE 1024
+char logbuf[BUFSIZE] = {0};
+int store = -1; /* negative for infinite logging, positive for limited logging */
+
+struct state_s {
+    void *func;
+    struct ly_ctx *ctx;
+};
+
+/* 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
+setup(void **state)
+{
+    struct state_s *s;
+
+    s = calloc(1, sizeof *s);
+    assert_non_null(s);
+
+#if ENABLE_LOGGER_CHECKING
+    ly_set_log_clb(logger, 1);
+#endif
+
+    assert_int_equal(LY_SUCCESS, ly_ctx_new(NULL, 0, &s->ctx));
+    *state = s;
+
+    return 0;
+}
+
+static int
+teardown(void **state)
+{
+    struct state_s *s = (struct state_s*)(*state);
+
+#if ENABLE_LOGGER_CHECKING
+    if (s->func) {
+        fprintf(stderr, "%s\n", logbuf);
+    }
+#endif
+
+    ly_ctx_destroy(s->ctx, NULL);
+    free(s);
+
+    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_yang(void **state)
+{
+    struct state_s *s = (struct state_s*)(*state);
+    s->func = test_yang;
+
+    struct lys_module *mod;
+    struct lysc_ext_instance *e;
+    struct lyext_metadata *ant;
+
+    const char *data = "module a {yang-version 1.1; namespace urn:tests:extensions:metadata:a; prefix a;"
+            "import ietf-yang-metadata {prefix md;}"
+            "feature f;"
+            "md:annotation x {"
+            "  description \"test\";"
+            "  if-feature f;"
+            "  reference \"test\";"
+            "  status \"current\";"
+            "  type uint8;"
+            "  units meters;"
+            "}}";
+    assert_non_null(mod = lys_parse_mem(s->ctx, data, LYS_IN_YANG));
+    assert_int_equal(1, LY_ARRAY_SIZE(mod->compiled->exts));
+    e = &mod->compiled->exts[0];
+    assert_non_null(ant = (struct lyext_metadata*)e->data);
+    assert_string_equal("meters", ant->units);
+
+    /* invalid */
+    /* missing mandatory type substatement */
+    data = "module aa {yang-version 1.1; namespace urn:tests:extensions:metadata:aa; prefix aa;"
+            "import ietf-yang-metadata {prefix md;}"
+            "md:annotation aa;}";
+    assert_null(lys_parse_mem(s->ctx, data, LYS_IN_YANG));
+    logbuf_assert("Missing mandatory keyword \"type\" as a child of \"md:annotation aa\". /aa:{extension='md:annotation'}/aa");
+
+    /* not allowed substatement */
+    data = "module aa {yang-version 1.1; namespace urn:tests:extensions:metadata:aa; prefix aa;"
+            "import ietf-yang-metadata {prefix md;}"
+            "md:annotation aa {default x;}}";
+    assert_null(lys_parse_mem(s->ctx, data, LYS_IN_YANG));
+    logbuf_assert("Invalid keyword \"default\" as a child of \"md:annotation aa\" extension instance. /aa:{extension='md:annotation'}/aa");
+
+    /* invalid cardinality of units substatement */
+    data = "module aa {yang-version 1.1; namespace urn:tests:extensions:metadata:aa; prefix aa;"
+            "import ietf-yang-metadata {prefix md;}"
+            "md:annotation aa {type string; units x; units y;}}";
+    assert_null(lys_parse_mem(s->ctx, data, LYS_IN_YANG));
+    logbuf_assert("Duplicate keyword \"units\". /aa:{extension='md:annotation'}/aa");
+
+    /* invalid cardinality of status substatement */
+    data = "module aa {yang-version 1.1; namespace urn:tests:extensions:metadata:aa; prefix aa;"
+            "import ietf-yang-metadata {prefix md;}"
+            "md:annotation aa {type string; status current; status obsolete;}}";
+    assert_null(lys_parse_mem(s->ctx, data, LYS_IN_YANG));
+    logbuf_assert("Duplicate keyword \"status\". /aa:{extension='md:annotation'}/aa");
+
+    /* invalid cardinality of status substatement */
+    data = "module aa {yang-version 1.1; namespace urn:tests:extensions:metadata:aa; prefix aa;"
+            "import ietf-yang-metadata {prefix md;}"
+            "md:annotation aa {type string; type uint8;}}";
+    assert_null(lys_parse_mem(s->ctx, data, LYS_IN_YANG));
+    logbuf_assert("Duplicate keyword \"type\". /aa:{extension='md:annotation'}/aa");
+
+    /* duplication of the same annotation */
+    data = "module aa {yang-version 1.1; namespace urn:tests:extensions:metadata:aa; prefix aa;"
+            "import ietf-yang-metadata {prefix md;}"
+            "md:annotation aa {type string;} md:annotation aa {type uint8;}}";
+    assert_null(lys_parse_mem(s->ctx, data, LYS_IN_YANG));
+    logbuf_assert("Extension plugin \"libyang 2 - metadata, version 1\": "
+            "Extension md:annotation is instantiated multiple times.) /aa:{extension='md:annotation'}/aa");
+
+    s->func = NULL;
+}
+
+int main(void)
+{
+    const struct CMUnitTest tests[] = {
+        cmocka_unit_test_setup_teardown(test_yang, setup, teardown),
+    };
+
+    return cmocka_run_group_tests(tests, NULL, NULL);
+}