update tests and README (#8)

* update tests and README

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README.md

@@ -12,16 +12,17 @@ pip install znfields
 
 ## Example
 
-The `znfields.field` supports all arguments from `dataclasses.field` with the additional `getter` argument.
+The `znfields.field` supports all arguments from `dataclasses.field` with the
+additional `getter` argument.
 
 ```python
 import dataclasses
 import znfields
 
-def example1_parameter_getter(self, name):
+def parameter_getter(self, name):
     return f"{name}:{self.__dict__[name]}"
 
 @dataclasses.dataclass
-class Example3(znfields.Base):
-    parameter: float = znfields.field(getter=example1_parameter_getter)
+class ClassWithParameter(znfields.Base):
+    parameter: float = znfields.field(getter=parameter_getter)
 ```

tests/test_znfields.py

@@ -1,21 +1,43 @@
 import dataclasses
-import znfields
+
 import pytest
 
+import znfields
+
 
 def example1_parameter_getter(self, name):
     return f"{name}:{self.__dict__[name]}"
 
 
+def stringify_list(self, name):
+    content = self.__dict__[name]
+    self.__dict__[name] = [str(x) for x in content]
+    # Can not return a copy to append to, but must be the same object
+    return self.__dict__[name]
+
+
 @dataclasses.dataclass
 class Example1(znfields.Base):
     parameter: float = znfields.field(getter=example1_parameter_getter)
 
 
+@dataclasses.dataclass
+class Example1WithDefault(znfields.Base):
+    parameter: float = znfields.field(getter=example1_parameter_getter, default=1)
+
+
+@dataclasses.dataclass
+class Example1WithDefaultFactory(znfields.Base):
+    parameter: list = znfields.field(getter=stringify_list, default_factory=list)
+
+
 def test_example1():
     example = Example1(parameter=1)
     assert example.parameter == "parameter:1"
 
+    exampe_w_default = Example1WithDefault()
+    assert exampe_w_default.parameter == "parameter:1"
+
 
 def test_example1_with_update():
     example = Example1(parameter=1)
@@ -125,3 +147,10 @@ class MyDataClass(znfields.Base):
 def test_metadata_must_be_dict():
     with pytest.raises(TypeError):
         znfields.field(metadata="not a dict", getter=lambda instance, name: None)
+
+
+def test_default_factory():
+    example = Example1WithDefaultFactory()
+    assert example.parameter == []
+    example.parameter.append(1)
+    assert example.parameter == ["1"]