Remove newline after code block open

CHANGES.md

@@ -12,6 +12,7 @@
 
 - Fix unstable formatting involving `# fmt: skip` comments without internal spaces
   (#2970)
+- trailing newlines are removed right after `def` statement (#3035)
 
 ### Preview style
 

src/black/lines.py

@@ -513,6 +513,12 @@ def _maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]:
         ):
             return before, 1
 
+        if (
+            self.previous_line
+            and self.previous_line.is_def
+            and depth == self.previous_line.depth + 1
+        ):
+            return 0, 0
         return before, 0
 
     def _maybe_empty_lines_for_class_or_def(

tests/data/newline_after_def1.py

@@ -0,0 +1,8 @@
+def foo():
+
+    print("The newline above me should be deleted!")
+
+# output
+
+def foo():
+    print("The newline above me should be deleted!")

tests/data/newline_after_def2.py

@@ -0,0 +1,10 @@
+def foo():
+
+
+
+    print("All the newlines above me should be deleted!")
+
+# output
+
+def foo():
+    print("All the newlines above me should be deleted!")

tests/data/newline_after_def3.py

@@ -0,0 +1,12 @@
+def f():
+
+    print("No newline above me!")
+
+    print("There is a newline above me, and that's OK!")
+
+# output
+
+def f():
+    print("No newline above me!")
+
+    print("There is a newline above me, and that's OK!")

tests/data/newline_after_def4.py

@@ -0,0 +1,12 @@
+def foo():
+
+    # There is a comment here
+
+    print("The newline above me should not be deleted!")
+
+# output
+
+def foo():
+    # There is a comment here
+
+    print("The newline above me should not be deleted!")

tests/data/newline_after_def5.py

@@ -0,0 +1,10 @@
+class Foo:
+    def bar(self):
+
+        print("The newline above me should be deleted!")
+
+# output
+
+class Foo:
+    def bar(self):
+        print("The newline above me should be deleted!")

tests/test_black.py

@@ -1451,7 +1451,6 @@ def test_newline_comment_interaction(self) -> None:
         black.assert_stable(source, output, mode=DEFAULT_MODE)
 
     def test_bpo_2142_workaround(self) -> None:
-
         # https://bugs.python.org/issue2142
 
         source, _ = read_data("missing_final_newline.py")

tests/test_format.py

@@ -50,6 +50,11 @@
     "function2",
     "function_trailing_comma",
     "import_spacing",
+    "newline_after_def1",
+    "newline_after_def2",
+    "newline_after_def3",
+    "newline_after_def4",
+    "newline_after_def5",
     "power_op_spacing",
     "remove_parens",
     "slices",