test(pypi): add argparse.bzl tests (#3697)

This simply adds extra unit tests to ensure that the code I have added
in #3691
is well covered.

Author: aignas

tests/pypi/argparse/BUILD.bazel

@@ -0,0 +1,3 @@
+load(":argparse_tests.bzl", "argparse_test_suite")
+
+argparse_test_suite(name = "argparse_tests")

tests/pypi/argparse/argparse_tests.bzl

@@ -0,0 +1,48 @@
+""
+
+load("@rules_testing//lib:test_suite.bzl", "test_suite")
+load("//python/private/pypi:argparse.bzl", "argparse")  # buildifier: disable=bzl-visibility
+
+_tests = []
+
+def _test_index_url(env):
+    env.expect.that_str(argparse.index_url([], "default")).equals("default")
+    env.expect.that_str(argparse.index_url([], None)).equals(None)
+
+    env.expect.that_str(argparse.index_url(["-i", "https://example.com/simple"], "default")).equals("https://example.com/simple")
+    env.expect.that_str(argparse.index_url(["--index-url", "https://example.com/simple"], "default")).equals("https://example.com/simple")
+    env.expect.that_str(argparse.index_url(["--index-url=https://example.com/simple"], "default")).equals("https://example.com/simple")
+
+    env.expect.that_str(argparse.index_url(["--extra-index-url", "https://extra.com", "-i", "https://index.com"], "default")).equals("https://index.com")
+
+_tests.append(_test_index_url)
+
+def _test_extra_index_url(env):
+    env.expect.that_collection(argparse.extra_index_url([], ["default"])).contains_exactly(["default"])
+    env.expect.that_collection(argparse.extra_index_url([], None)).contains_exactly([])
+
+    env.expect.that_collection(argparse.extra_index_url(["--extra-index-url", "https://extra.com/simple"], [])).contains_exactly(["https://extra.com/simple"])
+    env.expect.that_collection(argparse.extra_index_url(["--extra-index-url=https://extra.com/simple"], [])).contains_exactly(["https://extra.com/simple"])
+
+    env.expect.that_collection(argparse.extra_index_url(["--extra-index-url", "https://first.com", "--extra-index-url", "https://second.com"], [])).contains_exactly(["https://first.com", "https://second.com"])
+
+_tests.append(_test_extra_index_url)
+
+def _test_platform(env):
+    env.expect.that_collection(argparse.platform([], ["default"])).contains_exactly(["default"])
+    env.expect.that_collection(argparse.platform([], None)).contains_exactly([])
+
+    env.expect.that_collection(argparse.platform(["--platform", "manylinux_2_17_x86_64"], [])).contains_exactly(["manylinux_2_17_x86_64"])
+    env.expect.that_collection(argparse.platform(["--platform=manylinux_2_17_x86_64"], [])).contains_exactly(["manylinux_2_17_x86_64"])
+
+    env.expect.that_collection(argparse.platform(["--platform", "macosx_10_9_x86_64", "--platform", "linux_x86_64"], [])).contains_exactly(["macosx_10_9_x86_64", "linux_x86_64"])
+
+_tests.append(_test_platform)
+
+def argparse_test_suite(name):
+    """Create the test suite.
+
+    Args:
+        name: the name of the test suite
+    """
+    test_suite(name = name, basic_tests = _tests)