fix: remove DRY_RUN env var and --dry-run flag (#210)

Free the DRY_RUN env var name to be used for other purposes by function
authors.

The original intent of the DRY_RUN was to be used at build time for GCF
to validate function syntax without starting the server, but this was
never implemented. For local testing purposes, simply starting the
functions framework server is a better method.

README.md

@@ -322,7 +322,6 @@ You can configure the Functions Framework using command-line flags or environmen
 | `--signature-type` | `FUNCTION_SIGNATURE_TYPE` | The signature used when writing your function. Controls unmarshalling rules and determines which arguments are used to invoke your function. Default: `http`; accepted values: `http`, `event` or `cloudevent` |
 | `--source`         | `FUNCTION_SOURCE`         | The path to the file containing your function. Default: `main.py` (in the current working directory)                                                                                             |
 | `--debug`          | `DEBUG`                   | A flag that allows to run functions-framework to run in debug mode, including live reloading. Default: `False`                                                                                   |
-| `--dry-run`        | `DRY_RUN`                 | A flag that allows for testing the function build from the configuration without creating a server. Default: `False` |
 
 ## Enable Google Cloud Function Events
 

src/functions_framework/_cli.py

@@ -32,12 +32,6 @@
 @click.option("--host", envvar="HOST", type=click.STRING, default="0.0.0.0")
 @click.option("--port", envvar="PORT", type=click.INT, default=8080)
 @click.option("--debug", envvar="DEBUG", is_flag=True)
-@click.option("--dry-run", envvar="DRY_RUN", is_flag=True)
-def _cli(target, source, signature_type, host, port, debug, dry_run):
+def _cli(target, source, signature_type, host, port, debug):
     app = create_app(target, source, signature_type)
-    if dry_run:
-        click.echo("Function: {}".format(target))
-        click.echo("URL: http://{}:{}/".format(host, port))
-        click.echo("Dry run successful, shutting down.")
-    else:
-        create_server(app, debug).run(host, port)
+    create_server(app, debug).run(host, port)

tests/test_cli.py

@@ -69,18 +69,6 @@ def test_cli_no_arguments():
             [pretend.call("foo", None, "event")],
             [pretend.call("0.0.0.0", 8080)],
         ),
-        (
-            ["--target", "foo", "--dry-run"],
-            {},
-            [pretend.call("foo", None, "http")],
-            [],
-        ),
-        (
-            [],
-            {"FUNCTION_TARGET": "foo", "DRY_RUN": "True"},
-            [pretend.call("foo", None, "http")],
-            [],
-        ),
         (
             ["--target", "foo", "--host", "127.0.0.1"],
             {},