Allow importing helper/utility files in test files

[m-Peter]

Work towards: onflow/developer-grants#148

Description

Able to write modular test cases means a developer can import the utility functions from a cadence file to the test file. to avoid repetitive code.

(taken from onflow/developer-grants#148 (comment))

Note: By convention, we consider files that contain the _helper substring, to be helper/utility files. Of course, this is just an initial implementation detail, feel free to suggest an alternative. The main difficulty here is that we can't distinguish from a common.StringLocation, if we are dealing with a contract, or with a simple script containing Cadence code. The importResolver function, has business logic which rejects any imports that are not declared in the flow.json config file.

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For contributor use:

• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
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[codecov-commenter]

Codecov Report

Merging #1030 (44d85ad) into master (1b19872) will increase coverage by 0.08%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master    #1030      +/-   ##
==========================================
+ Coverage   39.65%   39.74%   +0.08%     
==========================================
  Files          37       37              
  Lines        1841     1847       +6     
==========================================
+ Hits          730      734       +4     
- Misses       1028     1029       +1     
- Partials       83       84       +1     

Flag	Coverage Δ
unittests	39.74% <66.66%> (+0.08%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
internal/test/test.go	40.20% <66.66%> (+1.74%)	⬆️

[turbolent]

Nice

[turbolent]

Suggested change

	testFiles := make(map[string][]byte, 0)
	testFiles[script.Filename] = script.Source
	testFiles := map[string][]byte{
	script.Filename: script.Source,
	}

[m-Peter]

Fixed in 6c6d174

[turbolent]

Maybe strip the file extension (path/filepath Ext()) and check the plain filename contains this as a suffix. Or is the idea that this allows both _helper and e.g. _helpers like in the two test files?

Also, maybe refactor this magic string into a constant and add a comment explaining it.

[m-Peter]

Or is the idea that this allows both _helper and e.g. _helpers like in the two test files?

Yes, exactly 👍 It might be the case that developers will put everything in a single helper file, or split them in several files. So I wanted to allow some flexibility in both plural & singular names.

Also, maybe refactor this magic string into a constant and add a comment explaining it.

Fixed in e920d18

[sideninja]

Looks good after Bastian comments.

[sideninja]

@m-Peter can I merge and release?