Add: show dict diffs in a way that's easier to understand

2 files changed, 71 insertions, 1 deletions

diff --git a/yarns/900-implements.yarn b/yarns/900-implements.yarn
index 1a42198..59da6c7 100644
--- a/yarns/900-implements.yarn
+++ b/yarns/900-implements.yarn
@@ -108,7 +108,12 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
     expected_text = get_next_match()
     expected = json.loads(expected_text)
     actual = json.loads(vars['body'])
-    assertEqual(expected, actual)
+    print('expected', json.dumps(expected, indent=4))
+    print('actual', json.dumps(actual, indent=4))
+    diff = dict_diff(expected, actual)
+    if diff is not None:
+        print(diff)
+        assert 0
 
     IMPLEMENTS THEN body text is "(.*)"
     expected = unescape(get_next_match())
diff --git a/yarns/lib.py b/yarns/lib.py
index b19ccf3..b4929fd 100644
--- a/yarns/lib.py
+++ b/yarns/lib.py
@@ -153,3 +153,68 @@ def delete(url, token):
     }
     r = requests.delete(url, headers=headers, verify=False)
     return r.status_code, r.headers['Content-Type'], dict(r.headers), r.text
+
+
+def dict_diff(a, b):
+    if not isinstance(a, dict):
+        return 'first value is not a dict'
+    if not isinstance(b, dict):
+        return 'second value is not a dict'
+
+    delta = []
+
+    for key in a:
+        if key not in b:
+            delta.append('second does not have key {}'.format(key))
+        elif isinstance(a[key], dict):
+            delta2 = dict_diff(a[key], b[key])
+            if delta2 is not None:
+                delta.append('key {}: dict values differ:'.format(key))
+                delta.append(delta2)
+        elif isinstance(a[key], list):
+            delta2 = list_diff(a[key], b[key])
+            if delta2 is not None:
+                delta.append('key {}: list values differ:'.format(key))
+                delta.append(delta2)
+        elif a[key] != b[key]:
+            delta.append('key {}: values differ'.format(key))
+            delta.append('  first value : {!r}'.format(a[key]))
+            delta.append('  second value: {!r}'.format(b[key]))
+
+    for key in b:
+        if key not in a:
+            delta.append('first does not have key {}'.format(key))
+
+    if delta:
+        return '\n'.join(delta)
+    return None
+
+
+def list_diff(a, b):
+    if not isinstance(a, list):
+        return 'first value is not a list'
+    if not isinstance(b, list):
+        return 'second value is not a list'
+
+    delta = []
+
+    for i in range(len(a)):
+        if i >= len(b):
+            delta.append('second list is shorter than first')
+            break
+        elif isinstance(a[i], dict):
+            delta2 = dict_diff(a[i], b[i])
+            if delta2 is not None:
+                delta.append('item {}: items are different dicts'.format(i))
+                delta.append(delta2)
+        elif a[i] != b[i]:
+            delta.append('item %d: values differ'.format(i))
+            delta.append('  first value : {!r}'.format(a[i]))
+            delta.append('  second value: {!r}'.format(b[i]))
+
+    if len(a) < len(b):
+        delta.append('first list is shorter than second')
+        
+    if delta:
+        return '\n'.join(delta)
+    return None