After figuring out how to encode email that will be read by a Japanese user (encoding for IS0-2022-JP and then base64 encoding), I need to figure out how to test that this actually works. I'm not fluent in Japanese. How does one go about testing that the email reads correctly? The message I'm sending would be written by my program in English, to be read by a Japanese user.
R – Testing email encoded for Japanese
If you have a hard time dealing with Japanese characters for test cases, why not test using wide latin? Wide latin is the latin character set formatted to monospaced and with their own code points in ISO-2020 and in unicode. If you get yourself a Japanese IME, you should be able to input them.
Here is some comparisons:
Since you will be able to enter and read everything with ease, this strategy might be good for testing.