test: update and add tests for refactored calculate_improvement function

tests/analyses/test_improvementfactor.py

@@ -5,7 +5,7 @@
 #       tests.analyses.test_improvementfactor.py is part of The RAMSTK Project
 #
 # All rights reserved.
-# Copyright 2019 Doyle Rowland doyle.rowland <AT> reliaqual <DOT> com
+# Copyright since 2007 Doyle Rowland doyle.rowland <AT> reliaqual <DOT> com
 """Test class for the improvement factor module."""
 
 # Third Party Imports
@@ -18,10 +18,131 @@
 @pytest.mark.unit
 @pytest.mark.calculation
 def test_calculate_improvementfactor():
-    """calculate_improvement() should return a tuple of improvement factor and weight."""
+    """calculate_improvement() should return a tuple of improvement factor and
+    weight."""
     _improvement, _weight = improvementfactor.calculate_improvement(
         3, 2, 4, user_float_1=2.6
     )
 
-    assert _improvement == 1.2
-    assert _weight == 12.48
+    assert _improvement == pytest.approx(1.2)
+    assert _weight == pytest.approx(12.48)
+
+
+@pytest.mark.unit
+@pytest.mark.calculation
+def test_calculate_improvementfactor_default_user_floats():
+    """calculate_improvement() should use default user_float_X values if not
+    provided."""
+    _improvement, _weight = improvementfactor.calculate_improvement(3, 2, 4)
+
+    assert _improvement == pytest.approx(1.2)
+    assert _weight == pytest.approx(4.8)  # 4 * 1.2 * (1.0 for each user_float)
+
+
+@pytest.mark.unit
+@pytest.mark.calculation
+def test_calculate_improvementfactor_negative_ranks():
+    """calculate_improvement() should raise a ValueError if ranks are negative."""
+    with pytest.raises(ValueError):
+        improvementfactor.calculate_improvement(-1, 2, 4)
+
+    with pytest.raises(ValueError):
+        improvementfactor.calculate_improvement(3, -2, 4)
+
+
+@pytest.mark.unit
+@pytest.mark.calculation
+def test_calculate_improvementfactor_negative_priority():
+    """calculate_improvement() should raise a ValueError if priority is zero or
+    negative."""
+    with pytest.raises(ValueError):
+        improvementfactor.calculate_improvement(3, 2, 0)  # Zero priority
+
+    with pytest.raises(ValueError):
+        improvementfactor.calculate_improvement(3, 2, -1)  # Negative priority
+
+
+@pytest.mark.unit
+@pytest.mark.calculation
+def test_calculate_improvementfactor_invalid_user_float():
+    """calculate_improvement() should raise a ValueError if user_float_X is non-
+    numeric."""
+    with pytest.raises(ValueError):
+        improvementfactor.calculate_improvement(3, 2, 4, user_float_1="invalid")
+
+
+@pytest.mark.unit
+@pytest.mark.calculation
+def test_calculate_improvementfactor_equal_ranks():
+    """calculate_improvement() should return an improvement factor of 1.0 when ranks are
+    equal."""
+    _improvement, _weight = improvementfactor.calculate_improvement(3, 3, 4)
+
+    assert _improvement == pytest.approx(1.0)
+    assert _weight == pytest.approx(4.0)  # priority * improvement factor * default
+    # user_float_X
+
+
+@pytest.mark.unit
+@pytest.mark.calculation
+def test_calculate_improvementfactor_max_rank_difference():
+    """calculate_improvement() shoul correctly handle large differences between
+    ranks."""
+    _improvement, _weight = improvementfactor.calculate_improvement(
+        10, 1, 3, user_float_1=2.0
+    )
+
+    assert _improvement == pytest.approx(2.8)  # 1.0 + 0.2 * (10 - 1)
+    assert _weight == pytest.approx(16.8)  # 3 * 2.8 * 2.0
+
+
+@pytest.mark.unit
+@pytest.mark.calculation
+def test_calculate_improvementfactor_zero_user_float():
+    """calculate_improvement() should raise a ValueError if any user_float_X is zero."""
+    with pytest.raises(ValueError):
+        improvementfactor.calculate_improvement(3, 2, 4, user_float_1=0.0)
+
+
+@pytest.mark.unit
+@pytest.mark.calculation
+def test_calculate_improvementfactor_all_user_floats_one():
+    """calculate_improvement() should calculate weight properly with user_float_X =
+    1.0."""
+    _improvement, _weight = improvementfactor.calculate_improvement(
+        5, 3, 6, user_float_1=1.0, user_float_2=1.0
+    )
+
+    assert _improvement == pytest.approx(1.4)
+    assert _weight == pytest.approx(8.4)  # 6 * 1.4 * (user_float defaults to 1.0)
+
+
+@pytest.mark.unit
+@pytest.mark.calculation
+def test_calculate_improvement_dynamic_user_floats():
+    """calculate_improvement() should dynamically handle any number of user floats."""
+    # Case with 2 user floats
+    _improvement, _weight = improvementfactor.calculate_improvement(
+        3, 2, 5, user_float_1=1.2, user_float_2=1.3
+    )
+    assert _improvement == pytest.approx(1.2)
+    assert _weight == pytest.approx(9.36)  # 5 * 1.2 * (1.2 * 1.3)
+
+    # Case with no user floats (defaults to 1.0)
+    _improvement, _weight = improvementfactor.calculate_improvement(3, 2, 5)
+    assert _improvement == pytest.approx(1.2)
+    assert _weight == pytest.approx(6.0)  # 5 * 1.2 * 1.0
+
+    # Case with 5 user floats
+    _improvement, _weight = improvementfactor.calculate_improvement(
+        3,
+        2,
+        5,
+        user_float_1=1.2,
+        user_float_2=1.3,
+        user_float_3=1.4,
+        user_float_4=1.5,
+        user_float_5=1.6,
+    )
+    assert _improvement == pytest.approx(1.2)
+    assert _weight == pytest.approx(31.4496)  # 5 * 1.2 * (1.2 * 1.3 * 1.4 * 1.5 * 1.6)