Merge pull request RustPython#1076 from corona10/complex_repr

Fix complex representation for negative imaginary number case.

Author: palaviv

tests/snippets/builtin_complex.py

@@ -135,3 +135,9 @@
 assert_raises(OverflowError, lambda: complex(10 ** 1000, 0), msg)
 assert_raises(OverflowError, lambda: complex(0, 10 ** 1000), msg)
 assert_raises(OverflowError, lambda: 0j + 10 ** 1000, msg)
+
+# str/repr
+assert '(1+1j)' == str(1+1j)
+assert '(1-1j)' == str(1-1j)
+assert '(1+1j)' == repr(1+1j)
+assert '(1-1j)' == repr(1-1j)

vm/src/obj/objcomplex.rs

@@ -204,7 +204,7 @@ impl PyComplex {
         if re == 0.0 {
             format!("{}j", im)
         } else {
-            format!("({}+{}j)", re, im)
+            format!("({}{:+}j)", re, im)
         }
     }