github.com/meulengracht/snapd@v0.0.0-20210719210640-8bde69bcc84e/strutil/limbuffer_test.go (about)

     1  // -*- Mode: Go; indent-tabs-mode: t -*-
     2  
     3  /*
     4   * Copyright (C) 2018 Canonical Ltd
     5   *
     6   * This program is free software: you can redistribute it and/or modify
     7   * it under the terms of the GNU General Public License version 3 as
     8   * published by the Free Software Foundation.
     9   *
    10   * This program is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU General Public License
    16   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    17   *
    18   */
    19  
    20  package strutil_test
    21  
    22  import (
    23  	. "gopkg.in/check.v1"
    24  
    25  	"github.com/snapcore/snapd/strutil"
    26  )
    27  
    28  type limitedBufferSuite struct{}
    29  
    30  var _ = Suite(&limitedBufferSuite{})
    31  
    32  func (s *limitedBufferSuite) TestLimitedBuffer(c *C) {
    33  	w := strutil.NewLimitedBuffer(100, 6)
    34  
    35  	data := []byte{'a'}
    36  	n, err := w.Write(data)
    37  	c.Assert(err, IsNil)
    38  	c.Assert(n, Equals, 1)
    39  	c.Assert(w.Bytes(), DeepEquals, []byte{'a'})
    40  
    41  	data = []byte("bcde")
    42  	n, err = w.Write(data)
    43  	c.Assert(err, IsNil)
    44  	c.Assert(n, Equals, 4)
    45  
    46  	n, err = w.Write([]byte("xyz"))
    47  	c.Assert(err, IsNil)
    48  	c.Assert(w.Bytes(), DeepEquals, []byte("cdexyz"))
    49  	c.Assert(n, Equals, 3)
    50  
    51  	n, err = w.Write([]byte("12"))
    52  	c.Assert(err, IsNil)
    53  	c.Assert(w.Bytes(), DeepEquals, []byte("exyz12"))
    54  	c.Assert(n, Equals, 2)
    55  
    56  	// eventually 2 times the size and this triggers the truncate in Write
    57  	n, err = w.Write([]byte("abcd"))
    58  	c.Assert(err, IsNil)
    59  	c.Assert(w.Bytes(), DeepEquals, []byte("12abcd"))
    60  	c.Assert(n, Equals, 4)
    61  
    62  	// more than maxBytes in a single write
    63  	n, err = w.Write([]byte("abcdefghijklmnopqrstuvwxyz"))
    64  	c.Assert(err, IsNil)
    65  	c.Assert(w.Bytes(), DeepEquals, []byte("uvwxyz"))
    66  	c.Assert(n, Equals, 26)
    67  }