Ensure that tests can run everywhere

Signed-off-by: Philippe Ombredanne <pombredanne@nexb.com>

Author: pombredanne

tests/data/pinned-requirements.txt-expected.json

@@ -4,7 +4,6 @@
     "tool_homepageurl": "https://github.com/nexB/python-inspector",
     "tool_version": "0.5.0",
     "options": [
-      "--requirement /home/pombreda/w421/python-inspector/tests/data/pinned-requirements.txt",
       "--index-url https://pypi.org/simple",
       "--python-version 38",
       "--operating-system linux",

tests/test_cli.py

@@ -119,18 +119,24 @@ def check_requirements_resolution(
     )
 
 
-def check_json_results(result_file, expected_file, regen=REGEN_TEST_FIXTURES):
+def check_json_results(result_file, expected_file, clean=True, regen=REGEN_TEST_FIXTURES):
     """
     Check the ``result_file`` JSON results against the ``expected_file``
     expected JSON results.
 
+    If ``clean`` is True, remove headers data that can change across runs to
+    provide stable test resultys.
+
     If ``regen`` is True the expected_file WILL BE overwritten with the new
     results from ``results_file``. This is convenient for updating tests
     expectations.
     """
     with open(result_file) as res:
         results = json.load(res)
 
+    if clean:
+        clean_results(results)
+
     if regen:
         with open(expected_file, "w") as reg:
             json.dump(results, reg, indent=2, separators=(",", ": "))
@@ -139,9 +145,23 @@ def check_json_results(result_file, expected_file, regen=REGEN_TEST_FIXTURES):
         with open(expected_file) as res:
             expected = json.load(res)
 
+            if clean:
+                clean_results(expected)
+
     assert results == expected
 
 
+def clean_results(results):
+    """
+    Return cleaned results removing transient values that can change across test
+    runs.
+    """
+    headers = results.get("headers", {})
+    options = headers.get("options", [])
+    headers["options"] = [o for o in options if not o.startswith("--requirement")]
+    return results
+
+
 def run_cli(options, cli=resolve_dependencies, expected_rc=0, env=None):
     """
     Run a command line resolution. Return a click.testing.Result object.