Fix Parameter.hasDefault (#1275)

When a default value is not set, hasDefault returns False. If
default=None is passed, hasDefault still returns False.

pyqtgraph/parametertree/Parameter.py

@@ -1,3 +1,4 @@
+# -*- coding: utf-8 -*-
 from ..Qt import QtGui, QtCore
 import os, weakref, re
 from ..pgcollections import OrderedDict
@@ -188,13 +189,11 @@ class Parameter(QtCore.QObject):
         
         self.addChildren(self.opts.pop('children', []))
         
-        self.opts['value'] = None
         if value is not None:
             self.setValue(value)
 
         if 'default' not in self.opts:
             self.opts['default'] = None
-            self.setDefault(self.opts['value'])
     
         ## Connect all state changed signals to the general sigStateChanged
         self.sigValueChanged.connect(lambda param, data: self.emitStateChanged('value', data))
@@ -420,7 +419,7 @@ class Parameter(QtCore.QObject):
 
     def hasDefault(self):
         """Returns True if this parameter has a default value."""
-        return 'default' in self.opts
+        return self.opts['default'] is not None
         
     def valueIsDefault(self):
         """Returns True if this parameter's value is equal to the default value."""

pyqtgraph/parametertree/tests/test_Parameter.py

@@ -0,0 +1,36 @@
+# -*- coding: utf-8 -*-
+import pytest
+from pyqtgraph.parametertree import Parameter
+
+
+def test_parameter_hasdefault():
+    opts = {'name': 'param', 'type': int, 'value': 1}
+
+    # default unspecified
+    p = Parameter(**opts)
+    assert not p.hasDefault()
+
+    p.setDefault(1)
+    assert p.hasDefault()
+    assert p.defaultValue() == 1
+
+    # default specified
+    p = Parameter(default=0, **opts)
+    assert p.hasDefault()
+    assert p.defaultValue() == 0
+
+
+@pytest.mark.parametrize('passdefault', [True, False])
+def test_parameter_hasdefault_none(passdefault):
+    # test that Parameter essentially ignores defualt=None, same as not passing
+    # a default at all
+    opts = {'name': 'param', 'type': int, 'value': 0}
+    if passdefault:
+        opts['default'] = None
+
+    p = Parameter(**opts)
+    assert not p.hasDefault()
+    assert p.defaultValue() is None
+
+    p.setDefault(None)
+    assert not p.hasDefault()