diff --git a/.coveragerc b/.coveragerc
new file mode 100644
index 00000000..26e44f99
--- /dev/null
+++ b/.coveragerc
@@ -0,0 +1,3 @@
+[run]
+concurrency = multiprocessing,thread
+source = optuna_dashboard/
diff --git a/.github/workflows/python-coverage.yml b/.github/workflows/python-coverage.yml
new file mode 100644
index 00000000..4bda6350
--- /dev/null
+++ b/.github/workflows/python-coverage.yml
@@ -0,0 +1,48 @@
+name: python coverage
+
+on:
+  push:
+    branches:
+      - master
+  pull_request: {}
+
+jobs:
+  coverage:
+    runs-on: ubuntu-latest
+
+    # Not intended for forks.
+    if: github.repository == 'optuna/optuna-dashboard'
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v3
+
+    - name: Setup Python
+      uses: actions/setup-python@v4
+      with:
+        python-version: '3.10'
+        architecture: x64
+
+    - name: Install dependencies
+      run: |
+        python -m pip install --progress-bar off --upgrade pip setuptools
+        pip install --progress-bar off .[optional]
+        pip install --progress-bar off .[test]
+        pip install --progress-bar off "optuna>=3.0.0"
+        pip install --progress-bar off .
+        echo 'import coverage; coverage.process_startup()' > sitecustomize.py
+    - name: Tests
+      env:
+        PYTHONPATH: .  # To invoke sitecutomize.py
+        COVERAGE_PROCESS_START: .coveragerc  # https://coverage.readthedocs.io/en/6.4.1/subprocess.html
+        COVERAGE_COVERAGE: yes  # https://github.com/nedbat/coveragepy/blob/65bf33fc03209ffb01bbbc0d900017614645ee7a/coverage/control.py#L255-L261
+      run: |
+        coverage run --source=optuna_dashboard -m pytest python_tests
+        coverage combine
+        coverage xml
+    - name: Upload coverage to Codecov
+      uses: codecov/codecov-action@v3
+      with:
+        token: ${{ secrets.CODECOV_TOKEN }}
+        file: ./coverage.xml
+        fail_ci_if_error: true
diff --git a/.github/workflows/python-tests.yml b/.github/workflows/python-tests.yml
index 612ddb59..8fee4e44 100644
--- a/.github/workflows/python-tests.yml
+++ b/.github/workflows/python-tests.yml
@@ -45,7 +45,8 @@ jobs:
         # python_tests requires optuna>=3.0.0 since it imports FloatDistribution
         run: |
           python -m pip install --progress-bar off --upgrade pip setuptools
-          pip install streamlit boto3 moto[s3] pytest
+          pip install --progress-bar off .[optional]
+          pip install --progress-bar off .[test]
           pip install --progress-bar off "optuna>=3.0.0"
           pip install --progress-bar off .
       - run: pytest python_tests
@@ -61,7 +62,8 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --progress-bar off --upgrade pip setuptools
-          pip install streamlit boto3 moto[s3] pytest
+          pip install --progress-bar off .[optional]
+          pip install --progress-bar off .[test]
           pip install --progress-bar off .
           python -m pip install --progress-bar off --upgrade git+https://github.com/optuna/optuna.git
       - run: pytest python_tests
diff --git a/.gitignore b/.gitignore
index 50ea6367..49c137e0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -28,6 +28,11 @@ docs/_generated/
 rustlib/target/
 rustlib/pkg/
 
+# Test
+.coverage
+.coverage.*
+coverage.xml
+
 # Others
 .envrc
 .idea/
diff --git a/pyproject.toml b/pyproject.toml
index d9c0082c..0555f701 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -41,6 +41,18 @@ docs = [
     "sphinx_rtd_theme",
 ]
 
+test = [
+    "coverage",
+    "pytest",
+    "moto[s3]",
+]
+
+optional = [
+    "streamlit",
+    "boto3",
+]
+
+
 [project.scripts]
 optuna-dashboard = "optuna_dashboard._cli:main"