Implement string conversion for workfunction class

src/py4vasp/_data/workfunction.py

@@ -12,6 +12,15 @@ class Workfunction(base.Refinery, graph.Mixin):
     In VASP you can compute the workfunction by setting the IDIPOL flag in the INCAR file.
     This class provides then the functionality to analyze the resulting potential."""
 
+    @base.data_access
+    def __str__(self):
+        data = self.to_dict()
+        return f"""workfunction along {data["direction"]}:
+    vacuum potential: {data["vacuum_potential"][0]:.3f} {data["vacuum_potential"][1]:.3f}
+    valence band maximum: {data["valence_band_maximum"]:.3f}
+    conduction band minimum: {data["conduction_band_minimum"]:.3f}
+    Fermi energy: {data["fermi_energy"]:.3f}"""
+
     @base.data_access
     def to_dict(self):
         bandgap = data.Bandgap.from_data(self._raw_data.reference_potential)

tests/conftest.py

@@ -626,7 +626,7 @@ def _workfunction(direction):
         average_potential=_make_arbitrary_data(shape),
         vacuum_potential=_make_arbitrary_data(shape=(2,)),
         reference_potential=_bandgap("nonpolarized"),
-        fermi_energy=1.0,
+        fermi_energy=1.234,
     )
 
 

tests/data/test_workfunction.py

@@ -2,6 +2,7 @@
 # Licensed under the Apache License 2.0 (http://www.apache.org/licenses/LICENSE-2.0)
 from unittest.mock import patch
 
+import numpy as np
 import pytest
 
 from py4vasp import data
@@ -66,6 +67,25 @@ def check_to_image(workfunction, filename_argument, expected_filename):
         fig.write_image.assert_called_once_with(workfunction._path / expected_filename)
 
 
+def test_print(workfunction, format_):
+    actual, _ = format_(workfunction)
+    reference = """\
+workfunction along {lattice_vector}:
+    vacuum potential: {vacuum1:.3f} {vacuum2:.3f}
+    valence band maximum: {vbm:.3f}
+    conduction band minimum: {cbm:.3f}
+    Fermi energy: {fermi_energy:.3f}"""
+    reference = reference.format(
+        lattice_vector=workfunction.ref.lattice_vector,
+        vacuum1=workfunction.ref.vacuum_potential[0],
+        vacuum2=workfunction.ref.vacuum_potential[1],
+        vbm=workfunction.ref.vbm,
+        cbm=workfunction.ref.cbm,
+        fermi_energy=workfunction.ref.fermi_energy,
+    )
+    assert actual == {"text/plain": reference}
+
+
 def test_factory_methods(raw_data, check_factory_methods):
     raw_workfunction = raw_data.workfunction("1")
     check_factory_methods(data.Workfunction, raw_workfunction)