Merge pull request RustPython#878 from sanxiyn/fix-just

Fix justification

Author: windelbouwman

tests/snippets/strings.py

@@ -57,6 +57,17 @@
 assert s.lstrip('^*') == 'RustPython*^'
 assert s.rstrip('^*') == '^*RustPython'
 
+s = 'RustPython'
+assert s.ljust(8) == 'RustPython'
+assert s.rjust(8) == 'RustPython'
+assert s.ljust(12) == 'RustPython  '
+assert s.rjust(12) == '  RustPython'
+assert s.ljust(12, '_') == 'RustPython__'
+assert s.rjust(12, '_') == '__RustPython'
+# The fill character must be exactly one character long
+assert_raises(TypeError, lambda: s.ljust(12, '__'))
+assert_raises(TypeError, lambda: s.rjust(12, '__'))
+
 c = 'hallo'
 assert c.capitalize() == 'Hallo'
 assert c.center(11, '-') == '---hallo---'

vm/src/obj/objstr.rs

@@ -740,7 +740,11 @@ impl PyString {
     ) -> PyResult<String> {
         let value = &self.value;
         let rep_char = Self::get_fill_char(&rep, vm)?;
-        Ok(format!("{}{}", value, rep_char.repeat(len)))
+        if len <= value.len() {
+            Ok(value.to_string())
+        } else {
+            Ok(format!("{}{}", value, rep_char.repeat(len - value.len())))
+        }
     }
 
     #[pymethod]
@@ -752,7 +756,11 @@ impl PyString {
     ) -> PyResult<String> {
         let value = &self.value;
         let rep_char = Self::get_fill_char(&rep, vm)?;
-        Ok(format!("{}{}", rep_char.repeat(len), value))
+        if len <= value.len() {
+            Ok(value.to_string())
+        } else {
+            Ok(format!("{}{}", rep_char.repeat(len - value.len()), value))
+        }
     }
 
     #[pymethod]