Add field test; add __pycache__ to gitignore

.gitignore

@@ -4,7 +4,7 @@
 *.a
 *.so
 *.aux
-*/__pycache__
+__pycache__
 optimizer/Tests/*.exe
 build
 CMakeCache.txt

tests/opal_src/PyOpal/PyObjects/test_field.py

+import unittest
+import tempfile
+import sys
+import subprocess
+import pyopal.objects.parser
+import pyopal.objects.field
+
+def run_encapsulated_test(file_name):
+    pyopal.objects.parser.initialise_from_opal_file(file_name)
+    print("Testing")
+    value = pyopal.objects.field.get_field_value(0, 1, 0, 0)
+    print(value)
+    return_code = abs(value[3]-2) > 1e-3
+    return return_code
+
+class FieldTest(unittest.TestCase):
+    def make_temp(self, a_string):
+        """Dump string to a temporary file for use in testing"""
+        my_temp = tempfile.NamedTemporaryFile(mode='w+')
+        my_temp.write(a_string)
+        my_temp.flush()
+        return my_temp
+
+    def test_get_field_value(self):
+        """Test that we can get out a field value"""
+        temp_file = self.make_temp(FieldTest.good_lattice)
+        if self.debug:
+            temp_stdout = None
+            temp_stderr = None
+        else:
+            temp_stdout = tempfile.TemporaryFile()
+            temp_stderr = subprocess.STDOUT
+        proc = subprocess.run(["python3", __file__, "run_unit_test_encapsulation", temp_file.name],
+                    stdout=temp_stdout, stderr=temp_stderr)
+        if temp_stdout:
+            temp_stdout.close() # why does this not use resource allocation?
+        self.assertEqual(proc.returncode, 0)
+
+    debug = 0
+    command = """
+import pyopal.objects.parser
+pyopal.objects.parser.initialise_from_opal_file(
+"""
+    good_lattice = """
+///////////////////////////////////////
+Title,string="Dummy lattice for testing";
+///
+
+OPTION, VERSION=20210100;
+
+field: VERTICALFFAMAGNET,
+        B0=2,
+        FIELD_INDEX=2,
+        MAX_HORIZONTAL_POWER=4,
+        END_LENGTH=0.01,
+        CENTRE_LENGTH=1000,
+        HEIGHT_NEG_EXTENT=4,
+        HEIGHT_POS_EXTENT=4,
+        WIDTH=2000,
+        BB_LENGTH=10;
+
+
+ringdef: RINGDEFINITION, HARMONIC_NUMBER=1, LAT_RINIT=1, LAT_PHIINIT=0,
+         LAT_THETAINIT=0.0, BEAM_PHIINIT=0, BEAM_PRINIT=0,
+         BEAM_RINIT=1, SYMMETRY=1, RFFREQ=1, IS_CLOSED=false,
+         MIN_R=0.1, MAX_R=2;
+
+l1: Line = (ringdef, field);
+
+Dist1: DISTRIBUTION, TYPE=gauss;
+
+Fs1:FIELDSOLVER, FSTYPE=None, MX=5, MY=5, MT=5,
+                 PARFFTX=true, PARFFTY=false, PARFFTT=false,
+                 BCFFTX=open, BCFFTY=open, BCFFTT=open,BBOXINCR=2;
+
+beam1: BEAM, PARTICLE=PROTON, pc=1, NPART=1, BCURRENT=1.6e-19, CHARGE=1.0, BFREQ=1;
+
+TRACK, LINE=l1, BEAM=beam1, MAXSTEPS=1, STEPSPERTURN=1;
+RUN, METHOD="CYCLOTRON-T", BEAM=beam1, FIELDSOLVER=Fs1, DISTRIBUTION=Dist1;
+ENDTRACK;
+STOP;
+"""
+
+if __name__ == "__main__":
+    print(sys.argv, len(sys.argv))
+    if len(sys.argv) > 2 and sys.argv[1] == "run_unit_test_encapsulation":
+        return_code = run_encapsulated_test(sys.argv[2])
+        sys.exit(return_code)
+    else:
+        FieldTest.debug = 1
+        unittest.main()