if default param is set, empty param can't overwrite it

[Fabian Halkivaha]

if i set in my deployment yaml file a default value for a parameter, i need to specify a new parameter with >= len() = 1 to overwrite the default value. It's not possible to overwrite the default value with an empty parameter.

Example:

Imagine this head of a senza deployment file (reduced version for simplicity):

SenzaInfo:
  StackName: hello-world
  Parameters:
    - Parameter1:
        Description: "Test Parameter"
        Default: "foobar"

if i execute senza create (or print) and provide no parameter, then the default param is used (which is correct). also this command executes as expected:

senza create test.yaml 1 Parameter1="barfoo"

BUT if i don't want that parameter to be set (it should be empty or None), then i would expect this to execute:

senza create test.yaml 1 Parameter1=""

But then senza is taking the default value ...

Usecase: In our application we have a feature toggle based on those Parameters. As soon as something is set here (in this case a password), the feature is activated. But if you want to deactivate the feature for a specfic deployment, you want to "unset" this parameter. for documentation reasons though, we have an example in our deployment file in the Default section (it's kind of a convention to use this field for documentation purposes as well, right?), so we can't unset this right now ...

Is this intended? if not i could take a look, if someone could point me to the location of this specific evaluation. I only did a first rough check, but could not find a if param: clause somewhere (which i think is causing this) ...

[João Santos]

Fixed by #486