New article creation flow

[MrOrz]

This PR rewrites initState handler, and creates askingArticleSubmissionConsent handler that replaces the original askingArticleSource handler.

What's covered

Chatbot Interactions within the red circle (LIFF not included)

Other things include:

• To support Postback buttons should be usable for the entire search session #49 , we remove issueAtbecause it changes every reply. data.sessionId is introduced instead. It changes only when the user submits new message.
• We are replacing all template reply with flex reply. This brings us benefits like:
  • Flex message is supported in desktop, while template message don't.
  • We no longer need to ask users to type "1", "2", "3" on desktop. This also removes the need to check user input lengh <= 3. Any text input that is not from LIFF can be considered as the start of a new search session.
• Use JWT as nonce in LIFF URLs. Since the JWT includes exp (expire timestamp claim), MockDate is introduced so that JWT can be deterministic across test runs.
• Adds mock to ga and asserts what is being sent to Google analytics in unit tests.
• Moves some of constants / functions that is going to share with LIFF to src/lib/sharedUtils.
• Adds ManipulationError. It differs from normal runtime error, because handleInput will catch ManipulationError and display its message in a nice flex reply. Very useful when we need to halt processing user input and display instruction to the user in reply.
• Removes isNonsenseText() logic because it's no longer used.
• Fix article search result (flex carousel) unit test in initState.

What's not covered

1. CHOOSING_ARTICLE and other state handlers are not updated accordingly, thus all other flows are not working yet
2. LIFF implementation is not done yet. The flow is tested by manually inputting prefix + option on LINE, mimicking user interaction in LIFF.
3. JWT token verification is not implemented on API @auth directive yet. Will implement when implementing LIFF.

Screenshot

Submission flow with valid source

Submission flow with source that cannot proceed

Image text not found

[coveralls]

Pull Request Test Coverage Report for Build 699

• 56 of 57 (98.25%) changed or added relevant lines in 6 files are covered.
• 60 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-19.2%) to 77.488%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/webhook/handlers/choosingArticle.js	0	1	0.0%

Files with Coverage Reduction	New Missed Lines	%
src/webhook/handlers/choosingArticle.js	60	0%

Totals
Change from base Build 690:	-19.2%
Covered Lines:	231
Relevant Lines:	295

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💛 - Coveralls

[nonumpa]

If process.env.IMAGE_MESSAGE_ENABLED is not true, image messages will not be tracked.
Maybe we can extract this along with index.js L168, index.js L179 to the beginning of process message.