diff --git a/tests/test_plugins.py b/tests/test_plugins.py
new file mode 100644
index 00000000..147050ac
--- /dev/null
+++ b/tests/test_plugins.py
@@ -0,0 +1,48 @@
+from bs4 import BeautifulSoup as Soup
+from .fixtures import (
+    app_client,
+)
+import pytest
+
+pytest.fixture(scope='session')(app_client)
+
+
+def test_plugins_dir_plugin(app_client):
+    response = app_client.get(
+        "/test_tables.json?sql=select+convert_units(100%2C+'m'%2C+'ft')",
+        gather_request=False
+    )
+    assert pytest.approx(328.0839) == response.json['rows'][0][0]
+
+
+def test_plugins_with_duplicate_js_urls(app_client):
+    # If two plugins both require jQuery, jQuery should be loaded only once
+    response = app_client.get(
+        "/test_tables",
+        gather_request=False
+    )
+    # This test is a little tricky, as if the user has any other plugins in
+    # their current virtual environment those may affect what comes back too.
+    # What matters is that https://example.com/jquery.js is only there once
+    # and it comes before plugin1.js and plugin2.js which could be in either
+    # order
+    scripts = Soup(response.body, 'html.parser').findAll('script')
+    srcs = [s['src'] for s in scripts if s.get('src')]
+    # No duplicates allowed:
+    assert len(srcs) == len(set(srcs))
+    # jquery.js loaded once:
+    assert 1 == srcs.count('https://example.com/jquery.js')
+    # plugin1.js and plugin2.js are both there:
+    assert 1 == srcs.count('https://example.com/plugin1.js')
+    assert 1 == srcs.count('https://example.com/plugin2.js')
+    # jquery comes before them both
+    assert srcs.index(
+        'https://example.com/jquery.js'
+    ) < srcs.index(
+        'https://example.com/plugin1.js'
+    )
+    assert srcs.index(
+        'https://example.com/jquery.js'
+    ) < srcs.index(
+        'https://example.com/plugin2.js'
+    )