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Currently the only ways to test your skills with text would be to use the test simulator in the Developer Console, through the ASK CLI or directly through SMAPI. If you built software using SMAPI this might be possible.
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SMAPI - Python - What do i need as the authorization header in the HTTP request ?
Request Alexa Skill API on local console
I'm not receiving Skill Messaging API requests in my skill anymore
ask-cli init fails under proxy after token fetch.