Add tests for MAC address representations

[jwieringa]

Adds tests to verify MAC Address conversion to different types of representations.

Successful tests:

% go test
PASS
ok  	github.com/RadiusNetworks/go-beacon	0.006s

Changing the data to show failing tests.

diff --git a/mac_address_test.go b/mac_address_test.go
index 6015091..7e0f12a 100644
--- a/mac_address_test.go
+++ b/mac_address_test.go
@@ -15,14 +15,14 @@ var testCases []mac
 func init() {
        testCases = []mac{
                {
-                       "fe:fd:55:c9:64:24",
+                       "be:fd:55:c9:64:24",
                        [6]byte{0x24, 0x64, 0xc9, 0x55, 0xfd, 0xfe},
-                       []byte{'"', 'f', 'e', ':', 'f', 'd', ':', '5', '5', ':', 'c', '9', ':', '6', '4', ':', '2', '4', '"'},
+                       []byte{'"', 'd', 'e', ':', 'f', 'd', ':', '5', '5', ':', 'c', '9', ':', '6', '4', ':', '2', '4', '"'},
                },
                {
-                       "29:fe:fd:41:21:20",
+                       "2b:fe:fd:41:21:20",
                        [6]byte{0x20, 0x21, 0x41, 0xfd, 0xfe, 0x29},
-                       []byte{'"', '2', '9', ':', 'f', 'e', ':', 'f', 'd', ':', '4', '1', ':', '2', '1', ':', '2', '0', '"'},
+                       []byte{'"', 'd', '9', ':', 'f', 'e', ':', 'f', 'd', ':', '4', '1', ':', '2', '1', ':', '2', '0', '"'},
                },
        }
 }

% go test
--- FAIL: TestMacString (0.00s)
    mac_address_test.go:34: result fe:fd:55:c9:64:24; want be:fd:55:c9:64:24
    mac_address_test.go:34: result 29:fe:fd:41:21:20; want 2b:fe:fd:41:21:20
--- FAIL: TestMacMarshalJSON (0.00s)
    mac_address_test.go:46: result "fe:fd:55:c9:64:24"; want "de:fd:55:c9:64:24"
    mac_address_test.go:46: result "29:fe:fd:41:21:20"; want "d9:fe:fd:41:21:20"
--- FAIL: TestMacUnmarshalJSON (0.00s)
    mac_address_test.go:56: result de:fd:55:c9:64:24; want be:fd:55:c9:64:24
    mac_address_test.go:56: result d9:fe:fd:41:21:20; want 2b:fe:fd:41:21:20
--- FAIL: TestParseMacAddress (0.00s)
    mac_address_test.go:66: result be:fd:55:c9:64:24; want fe:fd:55:c9:64:24
    mac_address_test.go:66: result 2b:fe:fd:41:21:20; want 29:fe:fd:41:21:20
FAIL
exit status 1
FAIL	github.com/RadiusNetworks/go-beacon	0.006s

[cupakromer]

Could this be:

Suggested change

	addr.UnmarshalJSON(tc.text)
	addr.UnmarshalJSON([]byte(tc.hex))

[cupakromer]

Both of these conditional checks are possibly replaceable with bytes.Equal:

		if !bytes.Equal(result, tc.text) {
			t.Errorf("result %s; want %s", result, tc.text)
		}