Preserve equals signs in CLI keyword values

CHANGES.md

@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- Fix CLI object parsing for string keyword values containing `=`.
 - `ValidSplit` now raises a clear error when it receives an `IterableDataset`, instead of an opaque `TypeError` about a missing length (#594)
 - `Checkpoint`'s sink message now reports the epoch the checkpoint was actually taken in, instead of the following one
 - Fix pickling a net with an `LRScheduler` callback dragging along a reference to the (potentially CUDA-resident) optimizer, which could prevent loading nets trained on CUDA on a CPU-only machine (#1096)

skorch/cli.py

@@ -94,7 +94,7 @@ def _parse_args_kwargs(params):
         if '=' not in param:
             args += (DefaultParseValue(param),)
         else:
-            k, v = param.split('=')
+            k, v = param.split('=', 1)
             kwargs[k.strip()] = DefaultParseValue(v)
     return args, kwargs
 

skorch/tests/test_cli.py

@@ -50,22 +50,25 @@ def parse_net_kwargs(self):
         from skorch.cli import parse_net_kwargs
         return parse_net_kwargs
 
-    def test_parse_net_kwargs(self, parse_net_kwargs):
+    @pytest.mark.parametrize('label', ['epoch', 'epoch=1', 'epoch=1=best'])
+    def test_parse_net_kwargs(self, parse_net_kwargs, label):
         kwargs = {
             'lr': 0.05,
             'max_epochs': 5,
             'module__num_units': 10,
             'module__nonlin': 'torch.nn.RReLU(0.123, upper=0.456)',
+            'module__config': f'builtins.dict(label="{label}")',
         }
         parsed_kwargs = parse_net_kwargs(kwargs)
 
-        assert len(parsed_kwargs) == 4
+        assert len(parsed_kwargs) == 5
         assert np.isclose(parsed_kwargs['lr'], 0.05)
         assert parsed_kwargs['max_epochs'] == 5
         assert parsed_kwargs['module__num_units'] == 10
         assert isinstance(parsed_kwargs['module__nonlin'], RReLU)
         assert np.isclose(parsed_kwargs['module__nonlin'].lower, 0.123)
         assert np.isclose(parsed_kwargs['module__nonlin'].upper, 0.456)
+        assert parsed_kwargs['module__config'] == {'label': label}
 
     @pytest.fixture
     def net_cls(self):