RustPython
diff --git a/‎tests/snippets/stdlib_io_bytesio.py‎
Lines changed: 16 additions & 0 deletions b/‎tests/snippets/stdlib_io_bytesio.py‎
Lines changed: 16 additions & 0 deletions
diff --git a/‎tests/snippets/stdlib_io_stringio.py‎
Lines changed: 14 additions & 0 deletions b/‎tests/snippets/stdlib_io_stringio.py‎
Lines changed: 14 additions & 0 deletions
diff --git a/‎vm/src/stdlib/io.rs‎
Lines changed: 26 additions & 1 deletion b/‎vm/src/stdlib/io.rs‎
Lines changed: 26 additions & 1 deletion
@@ -55,10 +55,26 @@ def test_05():
 
     assert f.getvalue() == bytes_string
 
+
+def test_06():
+    """
+        Tests readline
+    """
+    bytes_string =  b'Test String 6\nnew line is here\nfinished'
+
+    f = BytesIO(bytes_string)
+
+    assert f.readline() == b'Test String 6\n'
+    assert f.readline() == b'new line is here\n'
+    assert f.readline() == b'finished'
+    assert f.readline() == b''
+
+
 if __name__ == "__main__":
     test_01()
     test_02()
     test_03()
     test_04()
     test_05()
+    test_06()
 
@@ -51,8 +51,22 @@ def test_04():
     assert f.seek(0) == 0
     assert f.read(4) == 'Test'
 
+def test_05():
+    """
+        Tests readline
+    """
+    string =  'Test String 6\nnew line is here\nfinished'
+
+    f = StringIO(string)
+
+    assert f.readline() == 'Test String 6\n'
+    assert f.readline() == 'new line is here\n'
+    assert f.readline() == 'finished'
+    assert f.readline() == ''
+
 if __name__ == "__main__":
     test_01()
     test_02()
     test_03()
     test_04()
+    test_05()
@@ -86,6 +86,15 @@ impl BufferedIO {
     fn tell(&self) -> u64 {
         self.cursor.position()
     }
+
+    fn readline(&mut self) -> Option<String> {
+        let mut buf = String::new();
+
+        match self.cursor.read_line(&mut buf) {
+            Ok(_) => Some(buf),
+            Err(_) => None,
+        }
+    }
 }
 
 #[derive(Debug)]
@@ -150,6 +159,13 @@ impl PyStringIORef {
     fn tell(self, _vm: &VirtualMachine) -> u64 {
         self.buffer.borrow().tell()
     }
+
+    fn readline(self, vm: &VirtualMachine) -> PyResult<String> {
+        match self.buffer.borrow_mut().readline() {
+            Some(line) => Ok(line),
+            None => Err(vm.new_value_error("Error Performing Operation".to_string())),
+        }
+    }
 }
 
 fn string_io_new(
@@ -220,6 +236,13 @@ impl PyBytesIORef {
     fn tell(self, _vm: &VirtualMachine) -> u64 {
         self.buffer.borrow().tell()
     }
+
+    fn readline(self, vm: &VirtualMachine) -> PyResult<Vec<u8>> {
+        match self.buffer.borrow_mut().readline() {
+            Some(line) => Ok(line.as_bytes().to_vec()),
+            None => Err(vm.new_value_error("Error Performing Operation".to_string())),
+        }
+    }
 }
 
 fn bytes_io_new(
@@ -735,6 +758,7 @@ pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
         "write" => ctx.new_rustfunc(PyStringIORef::write),
         "getvalue" => ctx.new_rustfunc(PyStringIORef::getvalue),
         "tell" => ctx.new_rustfunc(PyStringIORef::tell),
+        "readline" => ctx.new_rustfunc(PyStringIORef::readline),
     });
 
     //BytesIO: in-memory bytes
@@ -746,7 +770,8 @@ pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
         "seekable" => ctx.new_rustfunc(PyBytesIORef::seekable),
         "write" => ctx.new_rustfunc(PyBytesIORef::write),
         "getvalue" => ctx.new_rustfunc(PyBytesIORef::getvalue),
-        "tell" => ctx.new_rustfunc(PyBytesIORef::tell)
+        "tell" => ctx.new_rustfunc(PyBytesIORef::tell),
+        "readline" => ctx.new_rustfunc(PyBytesIORef::readline),
     });
 
     py_module!(vm, "_io", {