BUG: Add tests and ensure proper testing of as_json values (pandas-dev#39701)

Author: alexprincel

pandas/tests/util/test_show_versions.py

@@ -1,10 +1,17 @@
+import json
+import os
 import re
 
 import pytest
 
 import pandas as pd
 
 
+@pytest.fixture
+def as_json(request):
+    return request.param
+
+
 @pytest.mark.filterwarnings(
     # openpyxl
     "ignore:defusedxml.lxml is no longer supported:DeprecationWarning"
@@ -26,21 +33,44 @@
     "ignore:Distutils:UserWarning"
 )
 @pytest.mark.filterwarnings("ignore:Setuptools is replacing distutils:UserWarning")
-def test_show_versions(capsys):
+@pytest.mark.parametrize('as_json', [True, False, 'test_output.json'], indirect=True)
+def test_show_versions(capsys, as_json, tmpdir):
     # gh-32041
-    pd.show_versions()
+    if isinstance(as_json, str):
+        as_json = os.path.join(tmpdir, as_json)
+
+    pd.show_versions(as_json=as_json)
     captured = capsys.readouterr()
     result = captured.out
 
-    # check header
-    assert "INSTALLED VERSIONS" in result
+    # check valid json is printed to the console if as_json is True
+    if as_json is True:
+        json.loads(result)
+
+    # check header for non-JSON console output
+    elif as_json is False:
+        assert "INSTALLED VERSIONS" in result
+
+        # check full commit hash
+        assert re.search(r"commit\s*:\s[0-9a-f]{40}\n", result)
+
+        # check required dependency
+        # 2020-12-09 npdev has "dirty" in the tag
+        assert re.search(r"numpy\s*:\s([0-9\.\+a-g\_]|dev)+(dirty)?\n", result)
+
+        # check optional dependency
+        assert re.search(r"pyarrow\s*:\s([0-9\.]+|None)\n", result)
+
+    elif isinstance(as_json, str):
+        # make sure that the file was created
+        assert os.path.exists(as_json)
 
-    # check full commit hash
-    assert re.search(r"commit\s*:\s[0-9a-f]{40}\n", result)
+        with open(as_json, 'r') as fd:
+            contents = fd.readlines()
+            str_contents = ''.join(contents)
 
-    # check required dependency
-    # 2020-12-09 npdev has "dirty" in the tag
-    assert re.search(r"numpy\s*:\s([0-9\.\+a-g\_]|dev)+(dirty)?\n", result)
+            # make sure that there was output to the file
+            assert str_contents
 
-    # check optional dependency
-    assert re.search(r"pyarrow\s*:\s([0-9\.]+|None)\n", result)
+            # check if file output is valid JSON
+            json.loads(str_contents)