Add support for different file versions and update tests (#63)

* Add support for different file versions and update tests

* Add tests

* Missing version Test

---------

Co-authored-by: Robert Timms <43040151+rtimms@users.noreply.github.com>
Co-authored-by: Ubham16 <you@example.com>

bpx/schema.py

@@ -60,6 +60,13 @@ class Header(ExtraBaseModel):
         description=('Model type ("SPM", "SPMe", "DFN")'),
     )
 
+    version: str = Field(
+        None,
+        alias="Version",
+        example="0.1.1",
+        description="BPX file version",  
+    )
+
 
 class Cell(ExtraBaseModel):
     """

tests/test_schema.py

@@ -10,6 +10,7 @@ class TestSchema(unittest.TestCase):
     def setUp(self):
         self.base = {
             "Header": {
+                "Version": "0.1.1",
                 "BPX": 1.0,
                 "Model": "DFN",
             },
@@ -216,6 +217,12 @@ def test_bad_model(self):
         with self.assertRaises(ValidationError):
             parse_obj_as(BPX, test)
 
+    def test_missing_version(self):
+        test = copy.copy(self.base)
+        del test["Header"]["Version"]
+        parsed_obj = parse_obj_as(BPX, test)
+        self.assertIsNone(parsed_obj.header.version)
+
     def test_bad_dfn(self):
         test = copy.copy(self.base_spm)
         test["Header"]["Model"] = "DFN"