diff --git a/tests/unit/anndata/test_anndata_factory.py b/tests/unit/anndata/test_anndata_factory.py
index 24cf25b3..004cd067 100644
--- a/tests/unit/anndata/test_anndata_factory.py
+++ b/tests/unit/anndata/test_anndata_factory.py
@@ -1,5 +1,7 @@
 """Unit tests for the AnnDataFactory class."""
 
+from unittest.mock import patch
+
 import numpy as np
 import pandas as pd
 import pytest
@@ -8,15 +10,21 @@
 from alphabase.psm_reader.keys import PsmDfCols
 
 
-def test_initialization_with_missing_columns():
-    """Test that an error is raised when the input DataFrame is missing required columns."""
-    psm_df = pd.DataFrame(
+def _get_test_psm_df():
+    """Return a test PSM DataFrame."""
+    return pd.DataFrame(
         {
-            PsmDfCols.RAW_NAME: ["raw1", "raw2"],
-            PsmDfCols.PROTEINS: ["protein1", "protein2"],
+            PsmDfCols.RAW_NAME: ["raw1", "raw1", "raw2"],
+            PsmDfCols.PROTEINS: ["protein1", "protein2", "protein1"],
+            PsmDfCols.INTENSITY: [100, 200, 300],
         }
     )
 
+
+def test_initialization_with_missing_columns():
+    """Test that an error is raised when the input DataFrame is missing required columns."""
+    psm_df = _get_test_psm_df().drop(columns=[PsmDfCols.INTENSITY])
+
     with pytest.raises(ValueError, match="Missing required columns: \['intensity'\]"):
         # when
         AnnDataFactory(psm_df)
@@ -24,13 +32,7 @@ def test_initialization_with_missing_columns():
 
 def test_create_anndata_with_valid_dataframe():
     """Test that an AnnData object is created correctly from a valid input DataFrame."""
-    psm_df = pd.DataFrame(
-        {
-            PsmDfCols.RAW_NAME: ["raw1", "raw1", "raw2"],
-            PsmDfCols.PROTEINS: ["protein1", "protein2", "protein1"],
-            PsmDfCols.INTENSITY: [100, 200, 300],
-        }
-    )
+    psm_df = _get_test_psm_df()
     factory = AnnDataFactory(psm_df)
 
     # when
@@ -39,7 +41,9 @@ def test_create_anndata_with_valid_dataframe():
     assert adata.shape == (2, 2)
     assert adata.obs_names.tolist() == ["raw1", "raw2"]
     assert adata.var_names.tolist() == ["protein1", "protein2"]
-    assert np.array_equal(adata.X, np.array([[100, 200], [300, np.nan]]))
+    assert np.array_equal(
+        adata.X, np.array([[100, 200], [300, np.nan]]), equal_nan=True
+    )
 
 
 def test_create_anndata_with_missing_intensity_values():
@@ -97,3 +101,20 @@ def test_create_anndata_with_empty_dataframe():
     adata = factory.create_anndata()
 
     assert adata.shape == (0, 0)
+
+
+@patch("alphabase.psm_reader.psm_reader.psm_reader_provider.get_reader")
+def test_from_files(mock_reader):
+    mock_reader.return_value.load.return_value = _get_test_psm_df()
+
+    factory = AnnDataFactory.from_files(["file1", "file2"], reader_type="maxquant")
+
+    # when
+    adata = factory.create_anndata()
+
+    assert adata.shape == (2, 2)
+    assert adata.obs_names.tolist() == ["raw1", "raw2"]
+    assert adata.var_names.tolist() == ["protein1", "protein2"]
+    assert np.array_equal(
+        adata.X, np.array([[100, 200], [300, np.nan]]), equal_nan=True
+    )