add support for printing the diff of AST trees when running tests (#3902)

[etc/vim.git] / src / black / debug.py

diff --git a/src/black/debug.py b/src/black/debug.py
index 150b44842dd1d9a0a852095aa4ee94e7e2e6b72d..cebc48765babd1ea989f64cf88cbe094f8370a60 100644 (file)
--- a/src/black/debug.py
+++ b/src/black/debug.py
@@ -1,5 +1,5 @@
-from dataclasses import dataclass
-from typing import Iterator, TypeVar, Union
+from dataclasses import dataclass, field
+from typing import Any, Iterator, List, TypeVar, Union
 
 from black.nodes import Visitor
 from black.output import out
@@ -14,26 +14,33 @@ T = TypeVar("T")
 @dataclass
 class DebugVisitor(Visitor[T]):
     tree_depth: int = 0
+    list_output: List[str] = field(default_factory=list)
+    print_output: bool = True
+
+    def out(self, message: str, *args: Any, **kwargs: Any) -> None:
+        self.list_output.append(message)
+        if self.print_output:
+            out(message, *args, **kwargs)
 
     def visit_default(self, node: LN) -> Iterator[T]:
         indent = " " * (2 * self.tree_depth)
         if isinstance(node, Node):
             _type = type_repr(node.type)
-            out(f"{indent}{_type}", fg="yellow")
+            self.out(f"{indent}{_type}", fg="yellow")
             self.tree_depth += 1
             for child in node.children:
                 yield from self.visit(child)
 
             self.tree_depth -= 1
-            out(f"{indent}/{_type}", fg="yellow", bold=False)
+            self.out(f"{indent}/{_type}", fg="yellow", bold=False)
         else:
             _type = token.tok_name.get(node.type, str(node.type))
-            out(f"{indent}{_type}", fg="blue", nl=False)
+            self.out(f"{indent}{_type}", fg="blue", nl=False)
             if node.prefix:
                 # We don't have to handle prefixes for `Node` objects since
                 # that delegates to the first child anyway.
-                out(f" {node.prefix!r}", fg="green", bold=False, nl=False)
-            out(f" {node.value!r}", fg="blue", bold=False)
+                self.out(f" {node.prefix!r}", fg="green", bold=False, nl=False)
+            self.out(f" {node.value!r}", fg="blue", bold=False)
 
     @classmethod
     def show(cls, code: Union[str, Leaf, Node]) -> None: