diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 86adf1d..8076da1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -4,7 +4,7 @@ name: API workflow
 on: [push, pull_request]
 
 jobs:
-  build:
+  api:
     runs-on: ubuntu-latest
     name: Test python API
     steps:
@@ -20,3 +20,40 @@ jobs:
       uses: codecov/codecov-action@v5
       with:
         token: ${{ secrets.CODECOV_TOKEN }}
+        flags: api
+
+  smiles:
+    runs-on: ubuntu-latest
+    name: Test python API
+    steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-python@v2
+      with:
+        python-version: '3.10'
+    - name: Install requirements
+      run: pip install -r api/requirements.txt
+    - name: Run tests and collect coverage
+      run: pytest --cov=smiles.smiles --cov-report=xml
+    - name: Upload coverage to Codecov
+      uses: codecov/codecov-action@v5
+      with:
+        token: ${{ secrets.CODECOV_TOKEN }}
+        flags: smiles
+
+  all:
+    runs-on: ubuntu-latest
+    name: Test python API
+    steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-python@v2
+      with:
+        python-version: '3.10'
+    - name: Install requirements
+      run: pip install -r api/requirements.txt
+    - name: Run tests and collect coverage
+      run: pytest --cov --cov-report=xml
+    - name: Upload coverage to Codecov
+      uses: codecov/codecov-action@v5
+      with:
+        token: ${{ secrets.CODECOV_TOKEN }}
+        flags: all
diff --git a/smiles/__init__.py b/smiles/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/smiles/smiles.py b/smiles/smiles.py
new file mode 100644
index 0000000..5cba42e
--- /dev/null
+++ b/smiles/smiles.py
@@ -0,0 +1,7 @@
+class Smiles:
+
+    def smiles():
+        return ':)'
+
+    def frowns():
+        return ':('
diff --git a/smiles/test_calculator.py b/smiles/test_calculator.py
new file mode 100644
index 0000000..39ae79b
--- /dev/null
+++ b/smiles/test_calculator.py
@@ -0,0 +1,5 @@
+from .smiles import Smiles
+
+
+def test_smiles():
+    assert Smiles.smiles() == ':)'