Disable 'package-that-throws-an-exception' except in spec that uses it

Loading this package logs a warning, so to minimize noise in the spec
console, it should only be loaded when `console.warn` is mocked.

spec/app/atom-spec.coffee

@@ -19,6 +19,7 @@ describe "the `atom` global", ->
       expect(rootView.activatePackage).toHaveBeenCalled()
 
     it "logs warning instead of throwing an exception if a package fails to load", ->
+      config.set("core.disabledPackages", [])
       spyOn(console, "warn")
       expect(-> atom.loadPackage("package-that-throws-an-exception")).not.toThrow()
       expect(console.warn).toHaveBeenCalled()

spec/spec-helper.coffee

@@ -35,6 +35,7 @@ beforeEach ->
   spyOn(config, 'save')
   config.set "editor.fontSize", 16
   config.set "editor.autoIndent", false
+  config.set "core.disabledPackages", ["package-that-throws-an-exception"]
 
   # make editor display updates synchronous
   spyOn(Editor.prototype, 'requestDisplayUpdate').andCallFake -> @updateDisplay()