Json stdout

[drewda]

Hi, here's a PR to add some functionality that is useful for developers chaining this together with other tools on the command line. This is related to at least one issue that has requested some aspects of this in the past. This is my first PR ever for this repo, so please do feel free to revise as needed or to hold if it conflicts with other planned functionality. Thanks.

Summary:

Enables JSON reports to be optionally output directly to stdout for piping to other programs, rather than being written to file system. Log output is suppressed. Involves changing how output directory is handled, but not intended to change existing default functionality in the CLI or the GUI.

closes #1194

Expected behavior:

• Adds an additional CLI argument
• Should not change GUI behavior
• CLI can now support usage such as:

java -jar cli/build/libs/gtfs-validator-0.1.0-SNAPSHOT-cli.jar -u https://data.trilliumtransit.com/gtfs/caltrain-ca-us/caltrain-ca-us.zip --stdout | jq '.notices[] .code'
"route_short_name_too_long"
"stop_without_stop_time"
"unknown_column"
"unknown_file"

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[emmambd]

Hi @drewda! Thanks for this great contribution and apologies for it slipping our notice in the midst of getting on top of emails after summer vacations. We plan to take a look soon.

[davidgamez]

Hi @drewda, great work!

I added a few minor comments that increase the readability of the code. I tested locally and it works as expected.

As a separate thought, I'm thinking of a fatal error scenario. In this case, as expected, the error is flushed to stderr, and nothing is output to stdout. I'm wondering if it makes sense to flush the "content" of the system_errors.json to the stdout so that the pipe processing can make decisions in case of errors. Otherwise, the pipe will get an empty string with no context of the error. This is an edge case where no human is looking at the screen. cc: @emmambd

[jcpitre]

@drewda Thank you for the contribution!
We created a fork of your fork so we could modify the branch. This means we needed a new PR: #2132
I am closing this PR since it's essentially replaced by #2132.

[drewda]

Thank you all for improving and merging this!