Example of Candid tools within Github Actions

[matthewhammer]

Finished by matthewhammer/motoko-bigtest#10

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Originally:

I would like to show examples of using the Candid tools within Github Actions:

• download and install candid tools (e.g., build from source, or get binary from Rust crates cache, or from a GH release?)
• test script captures a comprehensive log of all relevant canister behavior, as a candid value stored in a file (pipe output of dfx canister call MyCanister getFullLog)
• test script uses candiff to compare the latest log to an earlier one that is human readable, saved in the repo; any differences are also human readable (thanks to candiff)

[matthewhammer]

FYI: I also made a similar issue specific to BigTest, in that repo.

[chenyan-dfinity]

For the second item, this works:

didc decode `dfx canister call MyCanister getFullLog --output raw`

[matthewhammer]

PR for final item (and assembles all items all together):
matthewhammer/motoko-bigtest#8

[matthewhammer]

@chenyan-dfinity FYI there's some kind of mismatch between the parsing logic of didc and candiff
https://github.com/matthewhammer/motoko-bigtest/runs/1021556118#step:10:159

I think it concerns whether they expect enclosing parens around an input / output value, or not. (is it a unary tuple, or a value?)

[matthewhammer]

Any advice or ideas for the best resolution?

[chenyan-dfinity]

Yes, candiff is parsing a IDLValue, while didc is parsing IDLArgs (a vector of IDLValue). So pretty printing of IDLArgs always has a parenthesis. If you are comparing output from a method call (from dfx), it make more sense to work on IDLArgs, as method calls always return a sequence of values.

[matthewhammer]

Okay, I'll merge this as is, and fix the (superficial) mismatch in a subsequent PR to candiff. Thanks.

[matthewhammer]

matthewhammer/motoko-bigtest#10