diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index aafe8a4..8e203a1 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -1,5 +1,6 @@
 add_library(gemhadar_lib
     "fd_io.c"
+    "url.c"
 )
 target_include_directories(gemhadar_lib PUBLIC "include")
 set_property(TARGET gemhadar_lib PROPERTY C_STANDARD 11)
diff --git a/lib/include/url.h b/lib/include/url.h
new file mode 100644
index 0000000..ebb4532
--- /dev/null
+++ b/lib/include/url.h
@@ -0,0 +1,6 @@
+#ifndef URL_H
+#define URL_H
+
+int foo(void);
+
+#endif
diff --git a/lib/url.c b/lib/url.c
new file mode 100644
index 0000000..549f286
--- /dev/null
+++ b/lib/url.c
@@ -0,0 +1,6 @@
+#include "url.h"
+
+int foo(void)
+{
+    return 42;
+}
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index d720f59..b75557c 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -1,6 +1,9 @@
-add_library(test_lib
-    "test_io.c"
-)
-target_include_directories(test_lib PUBLIC "include")
+add_library(test_lib "test_io.c")
 set_property(TARGET test_lib PROPERTY C_STANDARD 11)
+target_include_directories(test_lib PUBLIC "include")
 target_link_libraries(test_lib gemhadar_lib)
+
+add_executable(url_tests "url_tests.c")
+set_property(TARGET test_lib PROPERTY C_STANDARD 11)
+target_link_libraries(url_tests gemhadar_lib test_lib)
+add_test(NAME "URL tests" COMMAND url_tests)
diff --git a/test/url_tests.c b/test/url_tests.c
new file mode 100644
index 0000000..cac8851
--- /dev/null
+++ b/test/url_tests.c
@@ -0,0 +1,19 @@
+#include "greatest.h"
+#include "url.h"
+
+TEST foo_returns_42(void)
+{
+    ASSERT_EQ(42, foo());
+    PASS();
+}
+
+GREATEST_MAIN_DEFS();
+
+int main(int argc, char *argv[])
+{
+    GREATEST_MAIN_BEGIN();
+
+    RUN_TEST(foo_returns_42);
+
+    GREATEST_MAIN_END();
+}