diff --git a/_unittests/ut_documentation/test_documentation_examples_show.py b/_unittests/ut_documentation/test_documentation_examples_show.py
new file mode 100644
index 00000000..515828ed
--- /dev/null
+++ b/_unittests/ut_documentation/test_documentation_examples_show.py
@@ -0,0 +1,35 @@
+"""
+@brief      test log(time=60s)
+"""
+import unittest
+import os
+from pyquickhelper.pycode import ExtTestCase
+
+
+class TestDocumentationExampleShow(ExtTestCase):
+
+    def test_documentation_examples_show(self):
+
+        this = os.path.abspath(os.path.dirname(__file__))
+        fold = os.path.normpath(
+            os.path.join(this, '..', '..', '_doc', 'examples'))
+        found = os.listdir(fold)
+        tested = 0
+        for name in sorted(found):
+            if not name.startswith("plot_") or not name.endswith(".py"):
+                continue
+
+            with self.subTest(name=name):
+                full_name = os.path.join(fold, name)
+                with open(full_name, "r", encoding="utf-8") as f:
+                    content = f.read()
+                if "plt.show()" in content and "# plt.show()" not in content:
+                    raise AssertionError(
+                        "plt.show() not found in %r." % name)
+                tested += 1
+        if tested == 0:
+            raise RuntimeError("No example was tested.")
+
+
+if __name__ == "__main__":
+    unittest.main()