github.com/siglens/siglens@v0.0.0-20240328180423-f7ce9ae441ed/pkg/segment/writer/metrics/compress/bit_reader_test.go (about)

     1  /*
     2  Copyright 2023.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package compress
    18  
    19  import (
    20  	"bytes"
    21  	"testing"
    22  
    23  	"github.com/stretchr/testify/assert"
    24  	"github.com/stretchr/testify/require"
    25  )
    26  
    27  func Test_bitReader_readBit(t *testing.T) {
    28  	var b byte = 0x1
    29  	for i := 0; i < 256; i++ {
    30  		buf := new(bytes.Buffer)
    31  		require.Nil(t, buf.WriteByte(b))
    32  		br := newBitReader(buf)
    33  		actual, err := br.readBit()
    34  		require.Nil(t, err)
    35  		assert.Equal(t, bit((b&0x80) != 0), actual)
    36  		b++
    37  	}
    38  }
    39  
    40  func Test_bitReader_readBits(t *testing.T) {
    41  	tests := []struct {
    42  		name       string
    43  		nbits      int
    44  		byteToRead byte
    45  		want       uint64
    46  		wantErr    error
    47  	}{
    48  		{
    49  			name:       "read a bit from 00000001",
    50  			nbits:      1,
    51  			byteToRead: 0x1,
    52  			want:       0,
    53  			wantErr:    nil,
    54  		},
    55  		{
    56  			name:       "read 5 bits from 00000001",
    57  			nbits:      5,
    58  			byteToRead: 0x1,
    59  			want:       0,
    60  			wantErr:    nil,
    61  		},
    62  		{
    63  			name:       "read 8 bits from 00000001",
    64  			nbits:      8,
    65  			byteToRead: 0x1,
    66  			want:       0x1,
    67  			wantErr:    nil,
    68  		},
    69  		{
    70  			name:       "read a bit from 11111111",
    71  			nbits:      1,
    72  			byteToRead: 0xff,
    73  			want:       0x1,
    74  			wantErr:    nil,
    75  		},
    76  		{
    77  			name:       "read 5 bits from 11111111",
    78  			nbits:      5,
    79  			byteToRead: 0xff,
    80  			want:       0x1f,
    81  			wantErr:    nil,
    82  		},
    83  		{
    84  			name:       "read 8 bits from 11111111",
    85  			nbits:      8,
    86  			byteToRead: 0xff,
    87  			want:       0xff,
    88  			wantErr:    nil,
    89  		},
    90  	}
    91  	for _, tt := range tests {
    92  		t.Run(tt.name, func(t *testing.T) {
    93  			buf := new(bytes.Buffer)
    94  			err := buf.WriteByte(tt.byteToRead)
    95  			require.Nil(t, err)
    96  			b := newBitReader(buf)
    97  			got, err := b.readBits(tt.nbits)
    98  			assert.Equal(t, tt.wantErr, err)
    99  			assert.Equal(t, tt.want, got)
   100  		})
   101  	}
   102  }
   103  
   104  func Test_bitReader_readByte(t *testing.T) {
   105  	var b byte = 0x1
   106  	for i := 0; i < 256; i++ {
   107  		buf := new(bytes.Buffer)
   108  		require.Nil(t, buf.WriteByte(b))
   109  		br := newBitReader(buf)
   110  		byt, err := br.readByte()
   111  		require.Nil(t, err)
   112  		assert.Equal(t, b, byt)
   113  		b++
   114  	}
   115  }