Add 'kn func emit' command

[lance]

Adds the kn func emit command. Usage is:

Emit event

Emits a CloudEvent, sending it to the deployed function.

Usage:
  func emit [flags]

Examples:

# Send a CloudEvent to the deployed function with no data and default values
# for source, type and ID
kn func emit

# Send a CloudEvent to the deployed function with the data found in ./test.json
kn func emit --file ./test.json

# Send a CloudEvent to the function running locally with a CloudEvent containing
# "Hello World!" as the data field, with a content type of "text/plain"
kn func emit --data "Hello World!" --content-type "text/plain" -s local

# Send a CloudEvent to the function running locally with an event type of "my.event"
kn func emit --type my.event --sink local

# Send a CloudEvent to the deployed function found at /path/to/fn with an id of "fn.test"
kn func emit --path /path/to/fn -i fn.test

# Send a CloudEvent to an arbitrary endpoint
kn func emit --sink "http://my.event.broker.com"


Flags:
  -c, --content-type string   The MIME Content-Type for the CloudEvent data  (Env: $FUNC_CONTENT_TYPE) (default "application/json")
  -d, --data string           Any arbitrary string to be sent as the CloudEvent data. Ignored if --file is provided  (Env: $FUNC_DATA)
  -f, --file string           Path to a local file containing CloudEvent data to be sent  (Env: $FUNC_FILE)
  -h, --help                  help for emit
  -i, --id string             CloudEvent ID (Env: $FUNC_ID) (default "205b5fc6-33b9-42ee-999a-04ca96c59b24")
  -p, --path string           Path to the project directory. Ignored when --sink is provided (Env: $FUNC_PATH) (default "/home/lanceball/src/github.com/boson-project/func")
  -k, --sink string           Send the CloudEvent to the function running at [sink]. The special value "local" can be used to send the event to a function running on the local host. When provided, the --path flag is ignored  (Env: $FUNC_SINK)
  -s, --source string         CloudEvent source (Env: $FUNC_SOURCE) (default "/boson/fn")
  -t, --type string           CloudEvent type  (Env: $FUNC_TYPE) (default "boson.fn")

Global Flags:
  -v, --verbose   print verbose logs

Still needed:

• CLI command implementation
• Client tests
• Configurable content type
• Fix lint errors
• Add documentation

Signed-off-by: Lance Ball lball@redhat.com

[matejvasek]

What if we used github.com/stretchr/testify/assert for prettier assertions?

[lkingland]

I like what assertion frameworks do in some languages, and have used several throughout the years, but (and I stress this is just a humble opinion), I have come to not like them. especially in Go. Having watched them steadily descend into madness repeatedly throughout the years, they are something I now avoid.

The standard built in language logic operators are are not only accessible to everyone without the need to learn a new API, but they also age better, and tend to teach the reader of the tests about the language, and the package being tested, better as one reads the tests. The code is being presented in a context similar to how it will be used in their code, rather than a somewhat contrived context of an almost, but not quite, natural language assertion syntax that is often just qirky enough to be confusing.

I am happy to go along with the majority opinion on this one, if others want to use an assertions framework I am game, but I feel compelled to make my jaded curmudgeon of a voice heard. I am also open to being educated on why they are worth the aforementioned problems!

[lance]

I am easy either way, but I don't think a new assertion library should be added in this PR. Willing to rebase on top of one that does though. :)

[lkingland]

Lookin' pretty good for a draft IMHO

[lance]

@boson-project/core I think this is ready for a review. PTAL.

[zroubalik]

Looking good! Minor nit on warning when both data and file is set.

[lkingland]

@lance I would take the purist approach and say that there is no way this is a state the developer intended, but is due to either a misconfiguration or misunderstanding, and should thus be an error.