Scale value error

Fixes #59 (closed)

test/residual_test/residual_test.py

@@ -2,16 +2,16 @@ import json
 
 from numpy.testing import assert_almost_equal, assert_equal
 from pydantic import parse_obj_as
-import pytest
 from typing import List
 
 from obspy.core import UTCDateTime
 from geomagio.residual import (
     calculate,
+    calculate_scale_value,
+    MeasurementType,
     Reading,
     SpreadsheetAbsolutesFactory,
     SpreadsheetSummaryFactory,
-    WebAbsolutesFactory,
 )
 
 
@@ -151,3 +151,26 @@ def test_BOU_20200422():
             actual=calculate(reading=reading, adjust_reference=False),
             decimal=0,
         )
+
+
+def test_calculate_scale_value():
+    """
+    Test behavior of calculate_scale_value for equal and non-equal residual values
+    """
+    reading = get_spreadsheet_absolutes(path="etc/residual/DED-20140952332.xlsm")
+    scale_measurements = reading[MeasurementType.NORTH_DOWN_SCALE]
+    # non-equal residual values
+    scale_value = calculate_scale_value(
+        measurements=scale_measurements,
+        inclination=0,
+        corrected_f=1,
+    )
+    assert scale_value == -0.29113906330841521
+    # equal residual values
+    scale_measurements[0].residual = scale_measurements[-1].residual
+    scale_value = calculate_scale_value(
+        measurements=scale_measurements,
+        inclination=0,
+        corrected_f=1,
+    )
+    assert scale_value is None