Make flushDeprecations non-destructive

[simonihmig]

When I already had something in my deprecation-workflow.js but a new deprecation got added, I would like to be able to update my existing config by calling deprecationWorkflow.flushDeprecations(). But this ignores all previous content and just emits a new config.

For example I have this:

import setupDeprecationWorkflow from 'ember-cli-deprecation-workflow';

setupDeprecationWorkflow({
  throwOnUnhandled: true,
  workflow: [
    { handler: 'log', matchId: 'deprecate-ember-error' },
  ],
});

Now when I run my tests (which hit deprecate-ember-error and let's say a new one called 'foo.bar') and call deprecationWorkflow.flushDeprecations()...

Expected

I would expect the existing workflow entry not to be touched, same as any other config like throwOnUnhandled.

import setupDeprecationWorkflow from 'ember-cli-deprecation-workflow';

setupDeprecationWorkflow({
  throwOnUnhandled: true,
  workflow: [
    { handler: 'log', matchId: 'deprecate-ember-error' },
    { handler: 'silence', matchId: 'foo.bar' },
  ],
});

Actual
The existing config is not taken into account at all. You get the same as if the initial config was empty. throwOnUnhandled is removed, the matching workflow is overridden with defaults (silence instead of log):

import setupDeprecationWorkflow from 'ember-cli-deprecation-workflow';

setupDeprecationWorkflow({
  workflow: [
    { handler: 'silence', matchId: 'deprecate-ember-error' },
    { handler: 'silence', matchId: 'foo.bar' },
  ],
});