--- /dev/null
+++ b/pyrfc3339/tests/test_all.py
@@ -0,0 +1,155 @@
+"""
+Test suite for pyRFC3339.
+
+"""
+
+import unittest
+import zoneinfo
+from datetime import datetime, timezone
+from zoneinfo import ZoneInfo
+
+from pyrfc3339 import generate, parse
+
+
+class TestCore(unittest.TestCase):
+    """
+    This test case contains tests to address cases not tested in the doctests,
+    as well as additional tests for end-to-end verification.
+
+    """
+
+    def test_zero_offset(self) -> None:
+        """
+        Both +00:00 and -00:00 are equivalent to the offset 'Z' (UTC).
+
+        """
+        timestamp = "2009-01-01T10:02:03+00:00"
+        dt = parse(timestamp)
+        self.assertEqual(dt.tzinfo, timezone.utc)
+
+        timestamp = "2009-01-01T10:02:03-00:00"
+        dt = parse(timestamp)
+        self.assertEqual(dt.tzinfo, timezone.utc)
+
+    def test_parse_microseconds(self) -> None:
+        """
+        Test parsing timestamps with microseconds.
+
+        """
+        timestamp = "2009-01-01T10:02:03.25Z"
+        dt = parse(timestamp)
+        self.assertEqual(dt.microsecond, 250000)
+
+    def test_generate_microseconds(self) -> None:
+        """
+        Test generating timestamps with microseconds.
+
+        """
+        dt = datetime(2009, 1, 1, 10, 2, 3, 500000, tzinfo=timezone.utc)
+        timestamp = generate(dt, microseconds=True)
+        self.assertEqual(timestamp, "2009-01-01T10:02:03.500000Z")
+
+    def test_mixed_case(self) -> None:
+        """
+        Timestamps may use either 'T' or 't' and either 'Z' or 'z'
+        according to :RFC:`3339`.
+
+        """
+        dt1 = parse("2009-01-01t10:01:02z")
+        dt2 = datetime(2009, 1, 1, 10, 1, 2, tzinfo=timezone.utc)
+
+        self.assertEqual(dt1, dt2)
+
+    def test_parse_naive_utc(self) -> None:
+        """
+        Test parsing a UTC timestamp to a naive datetime.
+
+        """
+        dt1 = parse("2009-01-01T10:01:02Z", produce_naive=True)
+        self.assertEqual(dt1.tzinfo, None)
+
+    def test_parse_naive_local(self) -> None:
+        """
+        Test that parsing a local timestamp to a naive datetime fails.
+
+        """
+        with self.assertRaises(ValueError):
+            parse("2009-01-01T10:01:02-04:00", produce_naive=True)
+
+    def test_generate_utc_parse_utc(self) -> None:
+        """
+        Generate a UTC timestamp and parse it into a UTC datetime.
+
+        """
+        dt1 = datetime.now(timezone.utc)
+
+        dt2 = parse(generate(dt1, microseconds=True))
+        self.assertEqual(dt1, dt2)
+
+    def test_generate_local_parse_local(self) -> None:
+        """
+        Generate a local timestamp and parse it into a local datetime.
+
+        """
+        eastern = ZoneInfo("US/Eastern")
+        dt1 = datetime.now(eastern)
+        dt2 = parse(generate(dt1, utc=False, microseconds=True), utc=False)
+        self.assertEqual(dt1, dt2)
+
+    def test_generate_local_parse_utc(self) -> None:
+        """
+        Generate a local timestamp and parse it into a UTC datetime.
+
+        """
+        eastern = ZoneInfo("US/Eastern")
+        dt1 = datetime.now(eastern)
+        dt2 = parse(generate(dt1, utc=False, microseconds=True))
+        self.assertEqual(dt1, dt2)
+
+    @unittest.skip("fails due to python/cpython#120713")
+    def test_three_digit_year(self) -> None:
+        dt = datetime(999, 1, 1, 0, 0, 0, tzinfo=timezone.utc)
+        self.assertEqual(generate(dt), "0999-01-01T00:00:00Z")
+
+
+class TestExhaustiveRoundtrip(unittest.TestCase):
+    """
+    This test case exhaustively tests parsing and generation by generating
+    a local RFC 3339 timestamp for every timezone supported by `zoneinfo`,
+    parsing that timestamp into a local datetime and a UTC datetime
+    and asserting that those represent the same instant.
+
+    """
+
+    def setUp(self) -> None:
+        self.available_timezones = zoneinfo.available_timezones()
+
+    def test_local_roundtrip(self) -> None:
+        """
+        Generates a local datetime using the given timezone,
+        produces a local timestamp from the datetime, parses the timestamp
+        to a local datetime, and verifies that the two datetimes are equal.
+
+        """
+        for tz_name in self.available_timezones:
+            with self.subTest(tz=tz_name):
+                tzinfo = ZoneInfo(tz_name)
+                dt1 = datetime.now(tzinfo)
+                timestamp = generate(dt1, utc=False, microseconds=True)
+                dt2 = parse(timestamp, utc=False)
+                self.assertEqual(dt1, dt2)
+
+    def test_utc_roundtrip(self) -> None:
+        """
+        Generates a local datetime using the given timezone,
+        produces a local timestamp from the datetime, parses the timestamp
+        to a UTC datetime, and verifies that the two datetimes are equal.
+
+        """
+        for tz_name in self.available_timezones:
+            with self.subTest(tz=tz_name):
+                tzinfo = ZoneInfo(tz_name)
+                dt1 = datetime.now(tzinfo)
+                timestamp = generate(dt1, utc=False, microseconds=True)
+                dt2 = parse(timestamp)
+                self.assertEqual(dt1, dt2)