Fix for removing items from dicts (#17)

* Fix for nested dict

* Replace nested test with simpler test

Also added pytest-cov to get an idea of what the code coverage is.
Apparently lines 98-99 of diff.py were exactly *not* covered.
Simply adding a test where an item is removed from a dict hits those
two lines.
Bonus: pytest-watch in dev tools.

Author: berendkleinhaneveld

.github/workflows/ci.yml

@@ -39,7 +39,7 @@ jobs:
       - name: Lint
         run: poetry run flake8
       - name: Test
-        run: poetry run pytest
+        run: poetry run pytest -v --cov=patchdiff --cov-report=term-missing
 
   build:
     name: Build and test wheel

patchdiff/diff.py

@@ -96,7 +96,7 @@ def diff_dicts(input: Dict, output: Dict, ptr: Pointer) -> Tuple[List, List]:
     output_keys = set(output.keys())
     for key in input_keys - output_keys:
         ops.append({"op": "remove", "path": ptr.append(key)})
-        rops.insert(0, {"op": "add", "path": ptr.append(key), "value": output[key]})
+        rops.insert(0, {"op": "add", "path": ptr.append(key), "value": input[key]})
     for key in output_keys - input_keys:
         ops.append(
             {

poetry.lock

@@ -16,6 +16,8 @@ flake8-black = "*"
 flake8-import-order = "*"
 flake8-print = "*"
 pytest = "*"
+pytest-cov = "*"
+pytest-watch = "*"
 twine = "*"
 
 [build-system]

pyproject.toml

@@ -122,6 +122,15 @@ def test_dicts():
     ]
 
 
+def test_dicts_remove_item():
+    a = {"a": 3, "b": 6}
+    b = {"a": 3}
+    ops, rops = diff(a, b)
+
+    assert ops == [{"op": "remove", "path": Pointer(["b"])}]
+    assert rops == [{"op": "add", "path": Pointer(["b"]), "value": 6}]
+
+
 def test_sets():
     a = {"a", "b"}
     b = {"a", "c"}