diff --git a/pyproject.toml b/pyproject.toml
index 91398a3e..0a37aa51 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -118,6 +118,9 @@ addopts = [
     "--color=yes",
     "--disable-pytest-warnings",
 ]
+markers = [
+    "online: run tests that require internet connection",
+]
 filterwarnings = ["error::FutureWarning"]  # todo: "error::DeprecationWarning"
 xfail_strict = true
 
diff --git a/tests/unittests/conftest.py b/tests/unittests/conftest.py
new file mode 100644
index 00000000..3aac31cf
--- /dev/null
+++ b/tests/unittests/conftest.py
@@ -0,0 +1,30 @@
+# Copyright The Lightning AI team.
+
+import os
+import shutil
+import tempfile
+from pathlib import Path
+
+import pytest
+
+from unittests import _PATH_ROOT
+
+_PATH_DOCS = os.path.join(_PATH_ROOT, "docs", "source")
+
+
+@pytest.fixture(scope="session")
+def temp_docs():
+    """Create a dummy documentation folder."""
+    # create a folder for docs
+    docs_folder = Path(tempfile.mkdtemp())
+    # copy all real docs from _PATH_DOCS to local temp_docs
+    for root, _, files in os.walk(_PATH_DOCS):
+        for file in files:
+            fpath = os.path.join(root, file)
+            temp_path = docs_folder / os.path.relpath(fpath, _PATH_DOCS)
+            temp_path.parent.mkdir(exist_ok=True, parents=True)
+            with open(fpath, "rb") as fopen:
+                temp_path.write_bytes(fopen.read())
+    yield str(docs_folder)
+    # remove the folder
+    shutil.rmtree(docs_folder.parent, ignore_errors=True)
diff --git a/tests/unittests/docs/test_retriever.py b/tests/unittests/docs/test_retriever.py
index 3c56bbc1..2b503e1f 100644
--- a/tests/unittests/docs/test_retriever.py
+++ b/tests/unittests/docs/test_retriever.py
@@ -1,30 +1,44 @@
 import os.path
 import shutil
 
+import pytest
 from lightning_utilities.docs import fetch_external_assets
 
-from unittests import _PATH_ROOT
 
-
-def test_retriever_s3():
-    path_docs = os.path.join(_PATH_ROOT, "docs", "source")
-    path_index = os.path.join(path_docs, "index.rst")
-    path_page = os.path.join(path_docs, "any", "extra", "page.rst")
+@pytest.mark.online()
+def test_retriever_s3(temp_docs):
+    # take the index page
+    path_index = os.path.join(temp_docs, "index.rst")
+    # copy it to another location to test depth
+    path_page = os.path.join(temp_docs, "any", "extra", "page.rst")
     os.makedirs(os.path.dirname(path_page), exist_ok=True)
     shutil.copy(path_index, path_page)
 
-    fetch_external_assets(docs_folder=path_docs)
+    def _get_line_with_figure(path_rst: str) -> str:
+        with open(path_rst, encoding="UTF-8") as fopen:
+            lines = fopen.readlines()
+        # find the first line with figure reference
+        return next(ln for ln in lines if ln.startswith(".. figure::"))
 
-    with open(path_index, encoding="UTF-8") as fopen:
-        body = fopen.read()
+    # validate the initial expectations
+    line = _get_line_with_figure(path_index)
     # that the image exists~
-    assert "Lightning.gif" in body
-    # but it is not sourced from S3
-    assert ".s3." not in body
+    assert "Lightning.gif" in line
+    # and it is sourced in S3
+    assert ".s3." in line
+
+    fetch_external_assets(docs_folder=temp_docs)
 
-    with open(path_page, encoding="UTF-8") as fopen:
-        body = fopen.read()
+    # validate the final state of index page
+    line = _get_line_with_figure(path_index)
     # that the image exists~
-    assert "Lightning.gif" in body
-    # check the proper depth
-    assert os.path.sep.join(["..", ".."]) in body
+    assert os.path.join("fetched-s3-assets", "Lightning.gif") in line
+    # but it is not sourced from S3
+    assert ".s3." not in line
+
+    # validate the final state of additional page
+    line = _get_line_with_figure(path_page)
+    # that the image exists in the proper depth
+    assert os.path.join("..", "..", "fetched-s3-assets", "Lightning.gif") in line
+    # but it is not sourced from S3
+    assert ".s3." not in line