Fail unit tests without 100% coverage (#206)

Author: Can Sarıgöl

setup.cfg

@@ -16,4 +16,4 @@ line_length = 88
 multi_line_output = 3
 
 [tool:pytest]
-addopts = --cov=httpx --cov=tests --cov-report=term-missing
+addopts = --cov=httpx --cov=tests --cov-report=term-missing --cov-fail-under=100

tests/test_utils.py

@@ -50,6 +50,12 @@ def test_bad_get_netrc_login():
     os.environ["NETRC"] = "wrongpath"
     assert get_netrc_login("url") is None
 
+    from httpx import utils
+
+    utils.NETRC_STATIC_FILES = ()
+    os.environ["NETRC"] = ""
+    assert utils.get_netrc_login("url") is None
+
 
 def test_get_netrc_login():
     os.environ["NETRC"] = "tests/.netrc"