Add generator close regression test

tests/test_ended_by_exception.py

@@ -5,9 +5,11 @@ f_lasti can be -1, and co_code[-1] would read the wrong opcode and misreport a
 normal return as "Call ended by exception".
 """
 
+import io
 import opcode
 from unittest.mock import Mock
 
+import pysnooper
 from pysnooper.tracer import call_ended_by_exception
 
 
@@ -39,3 +41,22 @@ def test_last_opcode_not_return_is_exception():
 def test_non_return_event_is_never_exception():
     co_code = bytes([opcode.opmap["NOP"], 0])
     assert call_ended_by_exception(_frame(co_code, 0), "call", None) is False
+
+
+def test_unstarted_generator_close_is_not_an_exception():
+    string_io = io.StringIO()
+
+    def gen(n):
+        for i in range(n):
+            yield i
+
+    @pysnooper.snoop(string_io, depth=2, color=False)
+    def main():
+        g = gen(5)
+        g.close()
+        return 42
+
+    assert main() == 42
+    output = string_io.getvalue()
+    assert "Call ended by exception" not in output
+    assert "Return value:.. 42" in output