IPv4Address: Unit tests

Problem:
- There is no direct unit testing of the IPv4Address functionality
  which makes refactoring difficult.

Solution:
- Add unit tests to cover the current functionality of
  IPv4Address. This will allow future refactorings with confidence.

AK/Tests/TestIPv4Address.cpp

@@ -0,0 +1,159 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/TestSuite.h>
+
+#include <AK/Endian.h>
+#include <AK/IPv4Address.h>
+
+TEST_CASE(should_default_contructor_with_0s)
+{
+    const IPv4Address addr {};
+
+    EXPECT(addr.is_zero());
+}
+
+TEST_CASE(should_construct_from_c_array)
+{
+    const u8 a[4] = { 1, 2, 3, 4 };
+    const IPv4Address addr(a);
+
+    EXPECT(!addr.is_zero());
+}
+
+TEST_CASE(should_construct_from_u32)
+{
+    const NetworkOrdered<u32> a = 0x11'22'33'44;
+    const IPv4Address addr(a);
+
+    EXPECT(!addr.is_zero());
+}
+
+TEST_CASE(should_get_octets_by_byte_offset)
+{
+    const u8 a[4] = { 1, 25, 39, 42 };
+    const IPv4Address addr(a);
+
+    EXPECT_EQ(1, addr[0]);
+    EXPECT_EQ(25, addr[1]);
+    EXPECT_EQ(39, addr[2]);
+    EXPECT_EQ(42, addr[3]);
+}
+
+TEST_CASE(should_convert_to_string)
+{
+    const u8 a[4] = { 1, 25, 39, 42 };
+    const IPv4Address addr(a);
+
+    EXPECT_EQ("1.25.39.42", addr.to_string());
+}
+
+TEST_CASE(should_make_ipv4_address_from_string)
+{
+    const auto addr = IPv4Address::from_string("192.168.0.1");
+
+    EXPECT(addr.has_value());
+    EXPECT_EQ(192, addr.value()[0]);
+    EXPECT_EQ(168, addr.value()[1]);
+    EXPECT_EQ(0, addr.value()[2]);
+    EXPECT_EQ(1, addr.value()[3]);
+}
+
+TEST_CASE(should_make_empty_optional_from_bad_string)
+{
+    const auto addr = IPv4Address::from_string("bad string");
+
+    EXPECT(!addr.has_value());
+}
+
+TEST_CASE(should_make_empty_optional_from_out_of_range_values)
+{
+    const auto addr = IPv4Address::from_string("192.168.0.500");
+
+    EXPECT(!addr.has_value());
+}
+
+TEST_CASE(should_fill_d_octet_from_1_part)
+{
+    const auto addr = IPv4Address::from_string("1");
+
+    EXPECT(addr.has_value());
+    EXPECT_EQ(0, addr.value()[0]);
+    EXPECT_EQ(0, addr.value()[1]);
+    EXPECT_EQ(0, addr.value()[2]);
+    EXPECT_EQ(1, addr.value()[3]);
+}
+
+TEST_CASE(should_fill_a_and_d_octets_from_2_parts)
+{
+    const auto addr = IPv4Address::from_string("192.1");
+
+    EXPECT(addr.has_value());
+    EXPECT_EQ(192, addr.value()[0]);
+    EXPECT_EQ(0, addr.value()[1]);
+    EXPECT_EQ(0, addr.value()[2]);
+    EXPECT_EQ(1, addr.value()[3]);
+}
+
+TEST_CASE(should_fill_a_b_d_octets_from_3_parts)
+{
+    const auto addr = IPv4Address::from_string("192.168.1");
+
+    EXPECT(addr.has_value());
+    EXPECT_EQ(192, addr.value()[0]);
+    EXPECT_EQ(168, addr.value()[1]);
+    EXPECT_EQ(0, addr.value()[2]);
+    EXPECT_EQ(1, addr.value()[3]);
+}
+
+TEST_CASE(should_convert_to_in_addr_t)
+{
+    const u8 a[4] = { 1, 2, 3, 4 };
+    const IPv4Address addr(a);
+
+    EXPECT_EQ(0x04'03'02'01u, addr.to_in_addr_t());
+}
+
+TEST_CASE(should_convert_to_u32)
+{
+    const u8 a[4] = { 1, 2, 3, 4 };
+    const IPv4Address addr(a);
+
+    EXPECT_EQ(0x04'03'02'01u, addr.to_u32());
+}
+
+TEST_CASE(should_compare)
+{
+    const u8 a[4] = { 1, 2, 3, 4 };
+    const u8 b[4] = { 1, 2, 3, 5 };
+    const IPv4Address addr_a(a);
+    const IPv4Address addr_b(b);
+
+    EXPECT(addr_a != addr_b);
+    EXPECT(addr_a == addr_a);
+}
+
+TEST_MAIN(IPv4Address)