datasette install --upgrade option, closes #945

datasette/cli.py

@@ -235,9 +235,16 @@ def package(
 
 @cli.command()
 @click.argument("packages", nargs=-1, required=True)
-def install(packages):
+@click.option(
+    "-U", "--upgrade", is_flag=True, help="Upgrade packages to latest version"
+)
+def install(packages, upgrade):
     "Install Python packages - e.g. Datasette plugins - into the same environment as Datasette"
-    sys.argv = ["pip", "install"] + list(packages)
+    args = ["pip", "install"]
+    if upgrade:
+        args += ["--upgrade"]
+    args += list(packages)
+    sys.argv = args
     run_module("pip", run_name="__main__")
 
 

docs/plugins.rst

@@ -43,7 +43,15 @@ You can uninstall plugins with ``datasette uninstall``::
 
     datasette uninstall datasette-vega
 
-These ommands are thin wrappers around ``pip install`` and ``pip uninstall``, which ensure they run ``pip`` in the same virtual environment as Datasette itself.
+You can upgrade plugins with ``datasette install --upgrade`` or ``datasette install -U``::
+
+    datasette install -U datasette-vega
+
+This command can also be used to upgrade Datasette itself to the latest released version::
+
+    datasette install -U datasette
+
+These commands are thin wrappers around ``pip install`` and ``pip uninstall``, which ensure they run ``pip`` in the same virtual environment as Datasette itself.
 
 One-off plugins using --plugins-dir
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tests/test_cli.py

@@ -125,6 +125,15 @@ def test_install(run_module):
     ]
 
 
+@pytest.mark.parametrize("flag", ["-U", "--upgrade"])
+@mock.patch("datasette.cli.run_module")
+def test_install_upgrade(run_module, flag):
+    runner = CliRunner()
+    runner.invoke(cli, ["install", flag, "datasette"])
+    run_module.assert_called_once_with("pip", run_name="__main__")
+    assert sys.argv == ["pip", "install", "--upgrade", "datasette"]
+
+
 @mock.patch("datasette.cli.run_module")
 def test_uninstall(run_module):
     runner = CliRunner()