diff --git a/e2e_tests/conftest.py b/e2e_tests/conftest.py
index b9b8e36f..8d8eac3b 100644
--- a/e2e_tests/conftest.py
+++ b/e2e_tests/conftest.py
@@ -1,3 +1,4 @@
+import socket
 import threading
 from wsgiref.simple_server import make_server
 
@@ -211,6 +212,14 @@ def make_dummy_storage(study_name: str) -> optuna.storages.InMemoryStorage:
     return storage
 
 
+def get_free_port() -> int:
+    tcp = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    tcp.bind(("", 0))
+    _, port = tcp.getsockname()
+    tcp.close()
+    return port
+
+
 @pytest.fixture(scope="session", params=study_names)
 def storage(request: pytest.FixtureRequest) -> optuna.storages.InMemoryStorage:
     study_name = request.param
@@ -221,7 +230,7 @@ def storage(request: pytest.FixtureRequest) -> optuna.storages.InMemoryStorage:
 @pytest.fixture(scope="session")
 def server_url(request: pytest.FixtureRequest, storage: optuna.storages.InMemoryStorage) -> str:
     addr = "127.0.0.1"
-    port = 38080
+    port = get_free_port()
     app = wsgi(storage)
     httpd = make_server(addr, port, app)
     thread = threading.Thread(target=httpd.serve_forever)
@@ -234,4 +243,15 @@ def server_url(request: pytest.FixtureRequest, storage: optuna.storages.InMemory
 
     request.addfinalizer(stop_server)
 
-    return f"http://{addr}:{port}/dashboard/"
+    return f"http://{addr}:{port}/dashboard"
+
+
+@pytest.fixture(scope="session")
+def browser_context_args(browser_context_args: dict) -> dict:
+    return {
+        **browser_context_args,
+        "viewport": {
+            "width": 1000,
+            "height": 3000,
+        },
+    }
diff --git a/e2e_tests/visual_regression_test.py b/e2e_tests/visual_regression_test.py
index 42b2190c..706ec2f3 100644
--- a/e2e_tests/visual_regression_test.py
+++ b/e2e_tests/visual_regression_test.py
@@ -7,8 +7,6 @@ def test_study_list(
     storage: optuna.storages.InMemoryStorage,
     server_url: str,
 ) -> None:
-    page.set_viewport_size({"width": 1000, "height": 3000})
-
     summaries = optuna.get_all_study_summaries(storage)
     study_id = summaries[0]._study_id
     study_name = summaries[0].study_name
@@ -22,3 +20,87 @@ def test_study_list(
     title = element.text_content()
     assert title is not None
     assert study_name in title
+
+
+def test_study_analytics(
+    page: Page,
+    storage: optuna.storages.InMemoryStorage,
+    server_url: str,
+) -> None:
+    summaries = optuna.get_all_study_summaries(storage)
+    study_id = summaries[0]._study_id
+    study_name = summaries[0].study_name
+    url = f"{server_url}/studies/{study_id}"
+
+    page.goto(url)
+    page.click(f"a[href='/dashboard/studies/{study_id}/analytics']")
+
+    element = page.query_selector(".MuiTypography-body1")
+    assert element is not None
+
+    title = element.text_content()
+    assert title is not None
+    assert study_name in title
+
+
+def test_trial_list(
+    page: Page,
+    storage: optuna.storages.InMemoryStorage,
+    server_url: str,
+) -> None:
+    summaries = optuna.get_all_study_summaries(storage)
+    study_id = summaries[0]._study_id
+    study_name = summaries[0].study_name
+    url = f"{server_url}/studies/{study_id}"
+
+    page.goto(url)
+    page.click(f"a[href='/dashboard/studies/{study_id}/trials']")
+
+    element = page.query_selector(".MuiTypography-body1")
+    assert element is not None
+
+    title = element.text_content()
+    assert title is not None
+    assert study_name in title
+
+
+def test_trial_table(
+    page: Page,
+    storage: optuna.storages.InMemoryStorage,
+    server_url: str,
+) -> None:
+    summaries = optuna.get_all_study_summaries(storage)
+    study_id = summaries[0]._study_id
+    study_name = summaries[0].study_name
+    url = f"{server_url}/studies/{study_id}"
+
+    page.goto(url)
+    page.click(f"a[href='/dashboard/studies/{study_id}/trialTable']")
+
+    element = page.query_selector(".MuiTypography-body1")
+    assert element is not None
+
+    title = element.text_content()
+    assert title is not None
+    assert study_name in title
+
+
+def test_trial_note(
+    page: Page,
+    storage: optuna.storages.InMemoryStorage,
+    server_url: str,
+) -> None:
+    summaries = optuna.get_all_study_summaries(storage)
+    study_id = summaries[0]._study_id
+    study_name = summaries[0].study_name
+    url = f"{server_url}/studies/{study_id}"
+
+    page.goto(url)
+    page.click(f"a[href='/dashboard/studies/{study_id}/note']")
+
+    element = page.query_selector(".MuiTypography-body1")
+    assert element is not None
+
+    title = element.text_content()
+    assert title is not None
+    assert study_name in title
diff --git a/optuna_dashboard/ts/searchSpace.ts b/optuna_dashboard/ts/searchSpace.ts
index 729f1f51..f0bd4006 100644
--- a/optuna_dashboard/ts/searchSpace.ts
+++ b/optuna_dashboard/ts/searchSpace.ts
@@ -3,9 +3,9 @@ import { useMemo } from "react"
 export const mergeUnionSearchSpace = (
   unionSearchSpace: SearchSpaceItem[]
 ): SearchSpaceItem[] => {
-  const knownElements = new Map<string, Distribution>()
+  let knownElements = new Map<string, Distribution>()
   unionSearchSpace.forEach((s) => {
-    const d = knownElements.get(s.name)
+    let d = knownElements.get(s.name)
     if (d === undefined) {
       knownElements.set(s.name, s.distribution)
       return
@@ -17,9 +17,12 @@ export const mergeUnionSearchSpace = (
       // CategoricalDistribution.choices will never be changed
       return
     }
-    d.low = Math.min(d.low, s.distribution.low)
-    d.high = Math.max(d.low, s.distribution.high)
-    knownElements.set(s.name, d)
+    const updated: Distribution = {
+      ...d,
+      low: Math.min(d.low, s.distribution.low),
+      high: Math.max(d.high, s.distribution.high),
+    }
+    knownElements.set(s.name, updated)
   })
   return Array.from(knownElements.keys())
     .sort((a, b) => (a > b ? 1 : a < b ? -1 : 0))