Add unit tests for ipv4_range_parse.

Covers single addresses, explicit ranges and the cidr mask boundaries.

test/src/test_command_ip.h

@@ -0,0 +1,25 @@
+#include <cppunit/TestFixture.h>
+#include <cppunit/extensions/HelperMacros.h>
+
+// ipv4_range_parse is a pure function, so this does not use test_fixture and
+// the mock and logging setup that comes with it.
+class TestCommandIp : public CppUnit::TestFixture {
+  CPPUNIT_TEST_SUITE(TestCommandIp);
+
+  CPPUNIT_TEST(test_single_address);
+  CPPUNIT_TEST(test_explicit_range);
+
+  CPPUNIT_TEST(test_cidr);
+  CPPUNIT_TEST(test_cidr_zero_mask);
+  CPPUNIT_TEST(test_cidr_full_mask);
+
+  CPPUNIT_TEST_SUITE_END();
+
+public:
+  void test_single_address();
+  void test_explicit_range();
+
+  void test_cidr();
+  void test_cidr_zero_mask();
+  void test_cidr_full_mask();
+};