diff --git a/tests/programs/negr_missing_lib.fzs b/tests/programs/negr_missing_lib.fzs
new file mode 100644
index 0000000..369e550
--- /dev/null
+++ b/tests/programs/negr_missing_lib.fzs
@@ -0,0 +1,10 @@
+extern "jopalib"
+{
+  type JopaLibType handle;
+
+  fn jopalib(int a, str b) JopaLibType;
+}
+
+JopaLibType a = jopalib(42, "jopa");
+printline(a);
+
diff --git a/tests/programs/pos_math_lib.fzs b/tests/programs/pos_math_lib.fzs
new file mode 100644
index 0000000..6de647f
--- /dev/null
+++ b/tests/programs/pos_math_lib.fzs
@@ -0,0 +1,8 @@
+extern "math" {
+  fn double_num(int num) int;
+}
+
+int initial = 42;
+int result = double_num(initial);
+printline($"initial value: {initial}, result of external function: {result}");
+
diff --git a/tests/programs/pos_renamed_lib.fzs b/tests/programs/pos_renamed_lib.fzs
new file mode 100644
index 0000000..54f8c47
--- /dev/null
+++ b/tests/programs/pos_renamed_lib.fzs
@@ -0,0 +1,8 @@
+extern "math" {
+  fn dnum(int num) int = "double_num";
+}
+
+int initial = 42;
+int result = dnum(initial);
+printline($"initial value: {initial}, result of external function: {result}");
+