Ignore JoinedStr for B018 (#216)

* Ignore JoinedStr for B018

* Improve tests

* Fix bug

Author: kasium

Diff for: bugbear.py

@@ -654,18 +654,15 @@ def check_for_b903(self, node):
         self.errors.append(B903(node.lineno, node.col_offset))
 
     def check_for_b018(self, node):
-        for index, subnode in enumerate(node.body):
+        for subnode in 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.Num,
                     ast.Bytes,
                     ast.NameConstant,
-                    ast.JoinedStr,
                     ast.List,
                     ast.Set,
                     ast.Dict,

Diff for: tests/b018_classes.py

@@ -1,6 +1,6 @@
 """
 Should emit:
-B018 - on lines 16-26, 30, 33
+B018 - on lines 17-26, 30, 33
 """
 
 
@@ -12,12 +12,12 @@ class Foo2:
     """abc"""
 
     a = 2
-    "str"  # Str
+    "str"  # Str (no raise)
+    f"{int}"  # JoinedStr (no raise)
     1j  # Number (complex)
     1  # Number (int)
     1.0  # Number (float)
     b"foo"  # Binary
-    f"{int}"  # JoinedStr
     True  # NameConstant (True)
     False  # NameConstant (False)
     None  # NameConstant (None)

Diff for: tests/b018_functions.py

@@ -1,6 +1,6 @@
 """
 Should emit:
-B018 - on lines 15-25, 29, 32
+B018 - on lines 16-25, 29, 32
 """
 
 
@@ -11,12 +11,12 @@ def foo1():
 def foo2():
     """my docstring"""
     a = 2
-    "str"  # Str
+    "str"  # Str (no raise)
+    f"{int}"  # JoinedStr (no raise)
     1j  # Number (complex)
     1  # Number (int)
     1.0  # Number (float)
     b"foo"  # Binary
-    f"{int}"  # JoinedStr
     True  # NameConstant (True)
     False  # NameConstant (False)
     None  # NameConstant (None)

Diff for: tests/test_bugbear.py

@@ -234,7 +234,7 @@ def test_b018_functions(self):
         bbc = BugBearChecker(filename=str(filename))
         errors = list(bbc.run())
 
-        expected = [B018(line, 4) for line in range(15, 26)]
+        expected = [B018(line, 4) for line in range(16, 26)]
         expected.append(B018(29, 4))
         expected.append(B018(32, 4))
         self.assertEqual(errors, self.errors(*expected))
@@ -244,7 +244,7 @@ def test_b018_classes(self):
         bbc = BugBearChecker(filename=str(filename))
         errors = list(bbc.run())
 
-        expected = [B018(line, 4) for line in range(16, 27)]
+        expected = [B018(line, 4) for line in range(17, 27)]
         expected.append(B018(30, 4))
         expected.append(B018(33, 4))
         self.assertEqual(errors, self.errors(*expected))