Add test file for cases pertaining magpylib#132

Author: lucasgcb

tests/test_tarcisBug.py

@@ -0,0 +1,70 @@
+import magpylib as magpy
+import numpy
+import unittest
+
+def test_rounding_error():
+    ## This describes the rotation bug. 
+    ## Once it is fixed, this test will break.
+    I = 1
+    d = 10e+05
+    p0 = [0,0,0]
+
+    c = magpy.source.current.Circular(curr=I, dim=d,pos=[0,0,d/4])
+
+    c.rotate(90,[0,0,1],anchor=[0,0,0])
+    c.rotate(90,[1,0,0],anchor=[0,0,0])
+    #print(c.angle) #These turn out differently for both cases.
+    #print(c.axis)
+
+    result1 = c.getB(p0)
+
+    c = magpy.source.current.Circular(curr=I, dim=d,pos=[0,0,d/4])
+
+    c.rotate(90,[1,0,0],anchor=[0,0,0])
+    #print(c.angle)
+    #print(c.axis)
+
+    result2 = c.getB(p0)
+    assert all(numpy.isclose(result1,result2)==True) is False
+
+
+def test_rounding_error_small_dimension():
+    ## This describes a case where the bug does not occur.
+    I = 1
+    d = 10e+03
+    p0 = [0,0,0]
+
+    c = magpy.source.current.Circular(curr=I, dim=d,pos=[0,0,d/4])
+
+    c.rotate(90,[0,0,1],anchor=[0,0,0])
+    c.rotate(90,[1,0,0],anchor=[0,0,0])
+
+    result1 = c.getB(p0)
+
+    c = magpy.source.current.Circular(curr=I, dim=d,pos=[0,0,d/4])
+
+    c.rotate(90,[1,0,0],anchor=[0,0,0])
+
+    result2 = c.getB(p0)
+    assert all(numpy.isclose(result1,result2)==True)
+
+def test_rounding_error_large_dimension():
+    ## This describes a case where the bug does not occur.
+    I = 1
+    d = 10e+08
+    p0 = [0,0,0]
+
+    c = magpy.source.current.Circular(curr=I, dim=d,pos=[0,0,d/4])
+
+    c.rotate(90,[0,0,1],anchor=[0,0,0])
+    c.rotate(90,[1,0,0],anchor=[0,0,0])
+
+    result1 = c.getB(p0)
+
+    c = magpy.source.current.Circular(curr=I, dim=d,pos=[0,0,d/4])
+
+    c.rotate(90,[1,0,0],anchor=[0,0,0])
+
+    result2 = c.getB(p0)
+    assert all(numpy.isclose(result1,result2)==True)
+