fix: Isolate pyhf contrib commands from rest of CLI (#1186)

* Move import pyhf.contrib.utils inside the contrib CLI functions
   - Guard the CLI API from missing extras without triggering warnings from using other modules CLI API
* Update the modules to reimport in tests

Author: matthewfeickert

src/pyhf/contrib/cli.py

@@ -3,8 +3,6 @@
 import click
 from pathlib import Path
 
-from . import utils
-
 logging.basicConfig()
 log = logging.getLogger(__name__)
 
@@ -22,6 +20,10 @@ def cli():
 
             $ python -m pip install pyhf[contrib]
     """
+    from . import utils  # Guard CLI from missing extra
+
+    # TODO: https://github.com/scikit-hep/pyhf/issues/863
+    _ = utils  # Placate pyflakes
 
 
 @cli.command()
@@ -57,6 +59,8 @@ def download(archive_url, output_directory, verbose, force, compress):
         :class:`~pyhf.exceptions.InvalidArchiveHost`: if the provided archive host name is not known to be valid
     """
     try:
+        from . import utils
+
         utils.download(archive_url, output_directory, force, compress)
 
         if verbose:

tests/test_scripts.py

@@ -562,7 +562,7 @@ def test_missing_contrib_extra(caplog):
         if "pyhf.contrib.utils" in sys.modules:
             reload(sys.modules["pyhf.contrib.utils"])
         else:
-            import_module("pyhf.cli")
+            import_module("pyhf.contrib.utils")
 
     with caplog.at_level(logging.ERROR):
         for line in [
@@ -577,10 +577,10 @@ def test_missing_contrib_extra(caplog):
 def test_missing_contrib_download(caplog):
     with mock.patch.dict(sys.modules):
         sys.modules["requests"] = None
-        if "pyhf.cli" in sys.modules:
-            reload(sys.modules["pyhf.cli"])
+        if "pyhf.contrib.utils" in sys.modules:
+            reload(sys.modules["pyhf.contrib.utils"])
         else:
-            import_module("pyhf.cli")
+            import_module("pyhf.contrib.utils")
 
         # Force environment for runner
         for module in [