diff --git a/spreadsheets/example_spreadsheet.xlsx b/spreadsheets/example_spreadsheet.xlsx
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diff --git a/tests/test_data.py b/tests/test_data.py
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+"""Pytest test suite for the filesystem module."""
+
+from pathlib import Path
+
+from cellveyor import data
+
+
+def test_access_dataframes() -> None:
+    spreadsheet_file_one = Path("spreadsheets/fake_spreadsheet.xlsx")
+    spreadsheet_file_two = Path("spreadsheets/example_spreadsheet.xlsx")
+    test_one = data.access_dataframes(spreadsheet_file_one)
+    test_two = data.access_dataframes(spreadsheet_file_two)
+    assert test_one != test_two
+
+
+def test_key_attribute_column_filter() -> None:
+    # Test key_attribute_column_filter function
+    dataframes_dict = data.access_dataframes(Path("spreadsheets/fake_spreadsheet.xlsx"))
+    sheet1_dataframe = dataframes_dict["Main"]
+
+    # Test filtering with a key attribute and columns regex
+    key_attribute_name = "Student GitHub"
+    column_regexp = "^(Summary Grade|Final Grade) .*$"
+    key_attribute_value = "gkapfham"
+    selected_columns, result_df = data.key_attribute_column_filter(
+        sheet1_dataframe, key_attribute_name, column_regexp, key_attribute_value
+    )
+
+    assert ("Summary Grade for Team Participation") in selected_columns.columns
+    assert ("Student GitHub") in result_df.columns
+    assert key_attribute_value in result_df["Student GitHub"].values