initialize/env: add notes about tests

initialize/env_test.go

@@ -14,6 +14,8 @@ func TestEnvironmentApply(t *testing.T) {
 		out   string
 	}{
 		{
+			// Substituting both values directly should always take precedence
+			// over environment variables
 			map[string]string{
 				"$public_ipv4":  "192.0.2.3",
 				"$private_ipv4": "192.0.2.203",
@@ -28,11 +30,13 @@ ExecStop=/usr/bin/echo 192.0.2.203
 ExecStop=/usr/bin/echo $unknown`,
 		},
 		{
+			// Substituting one value directly while falling back with the other
 			map[string]string{"$private_ipv4": "127.0.0.1"},
 			"$private_ipv4\n$public_ipv4",
 			"127.0.0.1\n1.2.3.4",
 		},
 		{
+			// Falling back to environment variables for both values
 			map[string]string{"foo": "bar"},
 			"$private_ipv4\n$public_ipv4",
 			"5.6.7.8\n1.2.3.4",