diff --git a/TODO b/TODO
index b43693de..3a64ff86 100644
--- a/TODO
+++ b/TODO
@@ -1,6 +1,7 @@
 task: sandbox modules
 task: rewrite README for 2.0
 task: rewrite i3 module
+task: improve test coverage
 fix: hide mpd controls if playlist is empty
 bug: allow empty formats
 bug: ntpd update crash
diff --git a/tests/components/test_command_line.cpp b/tests/components/test_command_line.cpp
new file mode 100644
index 00000000..40f8bd39
--- /dev/null
+++ b/tests/components/test_command_line.cpp
@@ -0,0 +1,118 @@
+#include <lemonbuddy/components/command_line.hpp>
+#include <lemonbuddy/utils/string.hpp>
+
+#include "../unit_test.hpp"
+
+using namespace lemonbuddy;
+using cli_parser = command_line::parser;
+
+// clang-format off
+const command_line::options g_opts{
+  command_line::option{"-f", "--flag", "Flag description"},
+  command_line::option{"-o", "--option", "Option description", "OPTION", {"foo", "bar", "baz"}},
+};
+// clang-format on
+
+class test_command_line : public unit_test {
+ public:
+  CPPUNIT_TEST_SUITE(test_command_line);
+  CPPUNIT_TEST(test_has_short);
+  CPPUNIT_TEST(test_has_long);
+  CPPUNIT_TEST(test_compare);
+  CPPUNIT_TEST(test_get);
+  CPPUNIT_TEST(test_missing_value);
+  CPPUNIT_TEST(test_invalid_value);
+  CPPUNIT_TEST(test_unrecognized);
+  CPPUNIT_TEST_SUITE_END();
+
+  void test_has_short() {
+    auto cli = get_instance();
+    cli.process_input(string_util::split("-f", ' '));
+    CPPUNIT_ASSERT_EQUAL(true, cli.has("flag"));
+    CPPUNIT_ASSERT_EQUAL(false, cli.has("option"));
+
+    cli = get_instance();
+    cli.process_input(string_util::split("-f -o foo", ' '));
+    CPPUNIT_ASSERT_EQUAL(true, cli.has("flag"));
+    CPPUNIT_ASSERT_EQUAL(true, cli.has("option"));
+
+    cli = get_instance();
+    cli.process_input(string_util::split("-o baz", ' '));
+    CPPUNIT_ASSERT_EQUAL(false, cli.has("flag"));
+    CPPUNIT_ASSERT_EQUAL(true, cli.has("option"));
+  }
+
+  void test_has_long() {
+    auto cli = get_instance();
+    cli.process_input(string_util::split("--flag", ' '));
+    CPPUNIT_ASSERT_EQUAL(true, cli.has("flag"));
+    CPPUNIT_ASSERT_EQUAL(false, cli.has("option"));
+
+    cli = get_instance();
+    cli.process_input(string_util::split("--flag --option=foo", ' '));
+    CPPUNIT_ASSERT_EQUAL(true, cli.has("flag"));
+    CPPUNIT_ASSERT_EQUAL(true, cli.has("option"));
+
+    cli = get_instance();
+    cli.process_input(string_util::split("--option=baz", ' '));
+    CPPUNIT_ASSERT_EQUAL(false, cli.has("flag"));
+    CPPUNIT_ASSERT_EQUAL(true, cli.has("option"));
+  }
+
+  void test_compare() {
+    auto cli = get_instance();
+    cli.process_input(string_util::split("-o baz", ' '));
+    CPPUNIT_ASSERT_EQUAL(true, cli.compare("option", "baz"));
+
+    cli = get_instance();
+    cli.process_input(string_util::split("--option=foo", ' '));
+    CPPUNIT_ASSERT_EQUAL(true, cli.compare("option", "foo"));
+  }
+
+  void test_get() {
+    auto cli = get_instance();
+    cli.process_input(string_util::split("--option=baz", ' '));
+    CPPUNIT_ASSERT_EQUAL(string{"baz"}, cli.get("option"));
+
+    cli = get_instance();
+    cli.process_input(string_util::split("--option=foo", ' '));
+    CPPUNIT_ASSERT_EQUAL(string{"foo"}, cli.get("option"));
+  }
+
+  void test_missing_value() {
+    auto input1 = string_util::split("--option", ' ');
+    auto input2 = string_util::split("-o", ' ');
+
+    using command_line::value_error;
+
+    CPPUNIT_ASSERT_THROW(get_instance().process_input(input1), value_error);
+    CPPUNIT_ASSERT_THROW(get_instance().process_input(input2), value_error);
+  }
+
+  void test_invalid_value() {
+    auto input1 = string_util::split("--option=invalid", ' ');
+    auto input2 = string_util::split("-o invalid_value", ' ');
+
+    using command_line::value_error;
+
+    CPPUNIT_ASSERT_THROW(get_instance().process_input(input1), value_error);
+    CPPUNIT_ASSERT_THROW(get_instance().process_input(input2), value_error);
+  }
+
+  void test_unrecognized() {
+    auto input1 = string_util::split("-x", ' ');
+    auto input2 = string_util::split("--unrecognized", ' ');
+
+    using command_line::argument_error;
+
+    CPPUNIT_ASSERT_THROW(get_instance().process_input(input1), argument_error);
+    CPPUNIT_ASSERT_THROW(get_instance().process_input(input2), argument_error);
+  }
+
+ private:
+  cli_parser get_instance() {
+    return cli_parser::configure<cli_parser>("cmd", g_opts).create<cli_parser>();
+  }
+};
+
+CPPUNIT_TEST_SUITE_REGISTRATION(test_command_line);