From 98829c3842c05b5b24305e275c5c5be7c782333c Mon Sep 17 00:00:00 2001
From: kasium <15907922+kasium@users.noreply.github.com>
Date: Mon, 22 Nov 2021 18:02:53 +0100
Subject: [PATCH] Improve B018 further (#202)

Catch also useless expressions on the first node in a body if the node is not a string (docstring).
---
 bugbear.py              | 8 ++++++--
 tests/b018_classes.py   | 3 ++-
 tests/b018_functions.py | 3 ++-
 tests/test_bugbear.py   | 6 ++++--
 4 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/bugbear.py b/bugbear.py
index efab5ab..d9d55a3 100644
--- a/bugbear.py
+++ b/bugbear.py
@@ -578,8 +578,12 @@ def check_for_b903(self, node):
         self.errors.append(B903(node.lineno, node.col_offset))
 
     def check_for_b018(self, node):
-        for subnode in node.body[1:]:
-            if isinstance(subnode, ast.Expr) and isinstance(
+        for index, subnode in enumerate(node.body):
+            if not isinstance(subnode, ast.Expr):
+                continue
+            if index == 0 and isinstance(subnode.value, ast.Str):
+                continue  # most likely a docstring
+            if isinstance(
                 subnode.value,
                 (
                     ast.Str,
diff --git a/tests/b018_classes.py b/tests/b018_classes.py
index 8a815d7..12195c0 100644
--- a/tests/b018_classes.py
+++ b/tests/b018_classes.py
@@ -1,6 +1,6 @@
 """
 Should emit:
-B018 - on lines 15-26, 31
+B018 - on lines 15-26, 30, 32
 """
 
 
@@ -27,5 +27,6 @@ class Foo2:
 
 
 class Foo3:
+    123
     a = 2
     "str"
diff --git a/tests/b018_functions.py b/tests/b018_functions.py
index afb7d26..9764274 100644
--- a/tests/b018_functions.py
+++ b/tests/b018_functions.py
@@ -1,6 +1,6 @@
 """
 Should emit:
-B018 - on lines 14-25, 30
+B018 - on lines 14-25, 29, 31
 """
 
 
@@ -26,5 +26,6 @@ def foo2():
 
 
 def foo3():
+    123
     a = 2
     "str"
diff --git a/tests/test_bugbear.py b/tests/test_bugbear.py
index 0ec95c4..0573e11 100644
--- a/tests/test_bugbear.py
+++ b/tests/test_bugbear.py
@@ -218,7 +218,8 @@ def test_b018_functions(self):
         errors = list(bbc.run())
 
         expected = [B018(line, 4) for line in range(14, 26)]
-        expected.append(B018(30, 4))
+        expected.append(B018(29, 4))
+        expected.append(B018(31, 4))
         self.assertEqual(errors, self.errors(*expected))
 
     def test_b018_classes(self):
@@ -227,7 +228,8 @@ def test_b018_classes(self):
         errors = list(bbc.run())
 
         expected = [B018(line, 4) for line in range(15, 27)]
-        expected.append(B018(31, 4))
+        expected.append(B018(30, 4))
+        expected.append(B018(32, 4))
         self.assertEqual(errors, self.errors(*expected))
 
     def test_b901(self):