resurrect app target

Author: Sam Schott

setup.cfg

@@ -93,8 +93,8 @@ briefcase.formats.linux =
     rpm = briefcase.platforms.linux.rpm
     snap = briefcase.platforms.linux.snap
 briefcase.formats.macOS =
+    app = briefcase.platforms.macOS.app
     xcode = briefcase.platforms.macOS.xcode
-    dmg = briefcase.platforms.macOS.dmg
     homebrew = briefcase.platforms.macOS.homebrew
 # briefcase.formats.tvOS =
 #     xcode = briefcase.platforms.tvOS.xcode

src/briefcase/platforms/macOS/app.py

@@ -0,0 +1,82 @@
+import subprocess
+
+from briefcase.commands import (
+    BuildCommand,
+    CreateCommand,
+    PackageCommand,
+    PublishCommand,
+    RunCommand,
+    UpdateCommand
+)
+from briefcase.config import BaseConfig
+from briefcase.exceptions import BriefcaseCommandError
+from briefcase.platforms.macOS import macOSMixin, macOSPackageMixin
+
+
+class macOSAppMixin(macOSMixin):
+    output_format = 'app'
+
+    def binary_path(self, app):
+        return self.bundle_path(app) / '{app.formal_name}.app'.format(app=app)
+
+    def distribution_path(self, app):
+        return self.binary_path(app)
+
+
+class macOSAppCreateCommand(macOSAppMixin, CreateCommand):
+    description = "Create and populate a macOS app."
+
+
+class macOSAppUpdateCommand(macOSAppMixin, UpdateCommand):
+    description = "Update an existing macOS app."
+
+
+class macOSAppBuildCommand(macOSAppMixin, BuildCommand):
+    description = "Build a macOS app."
+
+
+class macOSAppRunCommand(macOSAppMixin, RunCommand):
+    description = "Run a macOS app."
+
+    def run_app(self, app: BaseConfig, **kwargs):
+        """
+        Start the application.
+
+        :param app: The config object for the app
+        :param base_path: The path to the project directory.
+        """
+        print()
+        print('[{app.app_name}] Starting app...'.format(
+            app=app
+        ))
+        try:
+            print()
+            self.subprocess.run(
+                [
+                    'open',
+                    self.binary_path(app),
+                ],
+                check=True,
+            )
+        except subprocess.CalledProcessError:
+            print()
+            raise BriefcaseCommandError(
+                "Unable to start app {app.app_name}.".format(app=app)
+            )
+
+
+class macOSAppPackageCommand(macOSAppMixin, macOSPackageMixin, PackageCommand):
+    description = "Package a macOS app for distribution."
+
+
+class macOSAppPublishCommand(macOSAppMixin, PublishCommand):
+    description = "Publish a macOS app."
+
+
+# Declare the briefcase command bindings
+create = macOSAppCreateCommand  # noqa
+update = macOSAppUpdateCommand  # noqa
+build = macOSAppBuildCommand  # noqa
+run = macOSAppRunCommand  # noqa
+package = macOSAppPackageCommand  # noqa
+publish = macOSAppPublishCommand  # noqa