diff --git a/tests/plugins/test_plaintext_parser.py b/tests/plugins/test_plaintext_parser.py
new file mode 100644
index 0000000..2f78eff
--- /dev/null
+++ b/tests/plugins/test_plaintext_parser.py
@@ -0,0 +1,61 @@
+import uuid
+
+import pytest
+
+from proxy_pool.plugins.builtin.parsers.plaintext import PlaintextParser
+
+
+@pytest.fixture
+def parser():
+    return PlaintextParser()
+
+
+class TestSupports:
+    def test_matches_txt_extension(self, parser):
+        assert parser.supports("https://example.com/proxies.txt") is True
+
+    def test_matches_plain_in_url(self, parser):
+        assert parser.supports("https://example.com/plain-list") is True
+
+    def test_rejects_unrelated_url(self, parser):
+        assert parser.supports("https://example.com/proxies.json") is False
+
+
+class TestParse:
+    async def test_parses_valid_lines(self, parser):
+        raw = b"192.168.1.1:8080\n10.0.0.1:3128\n"
+        source_id = uuid.uuid4()
+
+        results = await parser.parse(raw, "http://example.com", source_id, "http")
+
+        assert len(results) == 2
+        assert results[0].ip == "192.168.1.1"
+        assert results[0].port == 8080
+        assert results[0].protocol == "http"
+        assert results[0].source_id == source_id
+
+    async def test_skips_invalid_lines(self, parser):
+        raw = b"192.168.1.1:8080\nnot a proxy\n\n# comment\n10.0.0.1:3128\n"
+
+        results = await parser.parse(raw, "http://example.com", None, "http")
+
+        assert len(results) == 2
+
+    async def test_handles_empty_input(self, parser):
+        results = await parser.parse(b"", "http://example.com", None, "http")
+
+        assert results == []
+
+    async def test_handles_bad_encoding(self, parser):
+        raw = b"192.168.1.1:8080\n\xff\xfe broken\n10.0.0.1:3128\n"
+
+        results = await parser.parse(raw, "http://example.com", None, "http")
+
+        assert len(results) == 2
+
+    async def test_uses_default_protocol(self, parser):
+        raw = b"1.2.3.4:1080\n"
+
+        results = await parser.parse(raw, "http://example.com", None, "socks5")
+
+        assert results[0].protocol == "socks5"
\ No newline at end of file
diff --git a/tests/plugins/test_tcp_checker.py b/tests/plugins/test_tcp_checker.py
new file mode 100644
index 0000000..6f3b8dc
--- /dev/null
+++ b/tests/plugins/test_tcp_checker.py
@@ -0,0 +1,32 @@
+import asyncio
+from datetime import datetime
+
+import pytest
+
+from proxy_pool.plugins.builtin.checkers.tcp_connect import TcpConnectChecker
+from proxy_pool.plugins.protocols import CheckContext
+
+
+@pytest.fixture
+def checker():
+    return TcpConnectChecker(timeout=2.0)
+
+
+@pytest.fixture
+def context():
+    return CheckContext(
+        started_at=datetime.now(),
+        http_client=None,
+    )
+
+
+class TestTcpConnect:
+    async def test_fails_on_unreachable_host(self, checker, context):
+        result = await checker.check("192.0.2.1", 1, "http", context)
+
+        assert result.passed is False
+        assert "timed out" in result.detail or "failed" in result.detail
+
+    async def test_never_skips(self, checker):
+        assert checker.should_skip("http") is False
+        assert checker.should_skip("socks5") is False
\ No newline at end of file