add --return-type to override test invoke return parameter type

[hal0x2328]

What current issue(s) does this address, or what feature is it adding?
Contract invocation results are displayed using the default return type of the contract, even though some operations will return different types than the default, requiring the user to manually convert results, e.g. from bytearray to integer

How did you solve this problem?
Added a --return-type argument to the sc invoke command to allow the user to override the contract's default return type during a test invoke

How did you make sure your solution works?
Manual testing

Are there any special changes in the code that we should be aware of?
No

Please check the following, if applicable:

• Did you add any tests?
• Did you run make lint?
• Did you run make test?
• Are you making a PR to a feature branch or development rather than master?
• Did you add an entry to CHANGELOG.rst? (if not, please do)

[jseagrave21]

This is a great addition. Will the code support the string equivalents of the ParameterTypes? I ask because I know it is a goal for users to be able to specify the input and output types with their string equivalents (i.e. "Integer" is acceptable, not just "02")
See #781

[jseagrave21]

I recommend adding some logic here to ensure only acceptable ParameterTypes are allowed.

[hal0x2328]

I asked myself when adding this option, does it add more value to add some sort of input sanity check rather than just educating the user through hitting an exception when they enter a bad parameter type? This is for advanced users after all. Personally I like the feedback loop approach, it doesn't really have any negative impact and it cuts down on the amount of code that needs to be maintained.

[ixje]

While true that it reduces code maintenance, we put in a lot of effort to get rid of exception throwing due to user input errors when we refactored the cli. I personally don't think that an advanced option or tool justifies not handling exceptions. In this case it's also as simple as doing

try:
   [ContractParameter.AsParameterType(ContractParameterType.FromString(return_type), item).ToJson() for item in results]
except ValueError:
    # inform user

[hal0x2328]

This is a great addition. Will the code support the string equivalents of the ParameterTypes? I ask because I know it is a goal for users to be able to specify the input and output types with their string equivalents (i.e. "Integer" is acceptable, not just "02")
See #781

It does support using the string equivalents but I don't use those in the example because the deployment convention has always been hex notation, both in neo-gui and neo-python, and all the documented examples use the hex notation. Unless it changes everywhere users are still going to need to know the mapping between hex and string parameter notation.

[ixje]

See #913 (comment)
Please add exception handling and add a test case for coverage. Thanks!

[hal0x2328]

Added exception handler and unit tests.

[ixje]

Thanks!