fix(amber): Do not add empty line to empty iterables

src/syrupy/extensions/amber/serializer.py

@@ -316,6 +316,8 @@ def __serialize_lines(
         include_type: bool = True,
         ends: str = "\n",
     ) -> str:
+        lines = ends.join(lines)
+        lines_end = "\n" if lines else ""
         return (
             f"{cls.with_indent(cls.object_type(data), depth)} " if include_type else ""
-        ) + f"{open_tag}\n{ends.join(lines)}\n{cls.with_indent(close_tag, depth)}"
+        ) + f"{open_tag}\n{lines}{lines_end}{cls.with_indent(close_tag, depth)}"

tests/__snapshots__/test_extension_amber.ambr

@@ -155,6 +155,10 @@
     ],
   }
 ---
+# name: test_dict[actual3]
+  <class 'dict'> {
+  }
+---
 # name: test_doubly_parametrized[bar-foo]
   'foo'
 ---
@@ -167,7 +171,27 @@
 # name: test_empty_snapshot.1
   ''
 ---
-# name: test_list
+# name: test_list[actual0]
+  <class 'list'> [
+  ]
+---
+# name: test_list[actual1]
+  <class 'list'> [
+    'this',
+    'is',
+    'a',
+    'list',
+  ]
+---
+# name: test_list[actual2]
+  <class 'list'> [
+    'contains',
+    'empty',
+    <class 'list'> [
+    ],
+  ]
+---
+# name: test_list[actual3]
   <class 'list'> [
     1,
     2,
@@ -294,6 +318,10 @@
     ),
   }
 ---
+# name: test_set[actual4]
+  <class 'set'> {
+  }
+---
 # name: test_string[0]
   ''
 ---
@@ -356,3 +384,7 @@
     },
   )
 ---
+# name: test_tuple.2
+  <class 'tuple'> (
+  )
+---

tests/test_extension_amber.py

@@ -76,6 +76,7 @@ def test_multiple_snapshots(snapshot):
 def test_tuple(snapshot):
     assert snapshot == ("this", "is", ("a", "tuple"))
     assert snapshot == ExampleTuple(a="this", b="is", c="a", d={"named", "tuple"})
+    assert snapshot == ()
 
 
 @pytest.mark.parametrize(
@@ -85,6 +86,7 @@ def test_tuple(snapshot):
         {"contains", "frozen", frozenset({"1", "2"})},
         {"contains", "tuple", (1, 2)},
         {"contains", "namedtuple", ExampleTuple(a=1, b=2, c=3, d=4)},
+        set(),
     ],
 )
 def test_set(snapshot, actual):
@@ -102,6 +104,7 @@ def test_set(snapshot, actual):
             frozenset({"1", "2"}): ["1", 2],
             ExampleTuple(a=1, b=2, c=3, d=4): {"e": False},
         },
+        {},
     ],
 )
 def test_dict(snapshot, actual):
@@ -114,8 +117,17 @@ def test_numbers(snapshot):
     assert snapshot == 2 / 6
 
 
-def test_list(snapshot):
-    assert snapshot == [1, 2, "string", {"key": "value"}]
+@pytest.mark.parametrize(
+    "actual",
+    [
+        [],
+        ["this", "is", "a", "list"],
+        ["contains", "empty", []],
+        [1, 2, "string", {"key": "value"}],
+    ],
+)
+def test_list(snapshot, actual):
+    assert actual == snapshot
 
 
 list_cycle = [1, 2, 3]