k8s.io/kubernetes@v1.29.3/pkg/util/tail/tail_test.go (about)

     1  /*
     2  Copyright 2016 The Kubernetes Authors.
     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 tail
    18  
    19  import (
    20  	"bytes"
    21  	"os"
    22  	"strings"
    23  	"testing"
    24  )
    25  
    26  func TestReadAtMost(t *testing.T) {
    27  	file, err := os.CreateTemp("", "TestFileReadAtMost")
    28  	if err != nil {
    29  		t.Fatalf("unable to create temp file")
    30  	}
    31  	defer os.Remove(file.Name())
    32  
    33  	line := strings.Repeat("a", blockSize)
    34  	testBytes := []byte(line + "\n" +
    35  		line + "\n" +
    36  		line + "\n" +
    37  		line + "\n" +
    38  		line[blockSize/2:]) // incomplete line
    39  
    40  	file.Write(testBytes)
    41  	testCases := []struct {
    42  		name          string
    43  		max           int64
    44  		longerThanMax bool
    45  		expected      string
    46  	}{
    47  		{
    48  			name:          "the max is negative",
    49  			max:           -1,
    50  			longerThanMax: true,
    51  			expected:      "",
    52  		},
    53  		{
    54  			name:          "the max is zero",
    55  			max:           0,
    56  			longerThanMax: true,
    57  			expected:      "",
    58  		},
    59  		{
    60  			name:          "the file length is longer than max",
    61  			max:           1,
    62  			longerThanMax: true,
    63  			expected:      "a",
    64  		},
    65  		{
    66  			name:          "the file length is longer than max and contains newlines",
    67  			max:           blockSize,
    68  			longerThanMax: true,
    69  			expected:      strings.Repeat("a", blockSize/2-1) + "\n" + strings.Repeat("a", blockSize/2),
    70  		},
    71  		{
    72  			name:          "the max is longer than file length ",
    73  			max:           4613,
    74  			longerThanMax: false,
    75  			expected:      string(testBytes),
    76  		},
    77  	}
    78  
    79  	for _, test := range testCases {
    80  		readAtMostBytes, longerThanMax, err := ReadAtMost(file.Name(), test.max)
    81  		if err != nil {
    82  			t.Fatalf("Unexpected failure %v", err)
    83  		}
    84  		if test.longerThanMax != longerThanMax {
    85  			t.Fatalf("Unexpected result on whether the file length longer than the max, want: %t, got: %t", test.longerThanMax, longerThanMax)
    86  		}
    87  		if test.expected != string(readAtMostBytes) {
    88  			t.Fatalf("Unexpected most max bytes, want: %s, got: %s", test.expected, readAtMostBytes)
    89  		}
    90  	}
    91  }
    92  
    93  func TestTail(t *testing.T) {
    94  	line := strings.Repeat("a", blockSize)
    95  	testBytes := []byte(line + "\n" +
    96  		line + "\n" +
    97  		line + "\n" +
    98  		line + "\n" +
    99  		line[blockSize/2:]) // incomplete line
   100  
   101  	for c, test := range []struct {
   102  		n     int64
   103  		start int64
   104  	}{
   105  		{n: -1, start: 0},
   106  		{n: 0, start: int64(len(line)+1) * 4},
   107  		{n: 1, start: int64(len(line)+1) * 3},
   108  		{n: 9999, start: 0},
   109  	} {
   110  		t.Logf("TestCase #%d: %+v", c, test)
   111  		r := bytes.NewReader(testBytes)
   112  		s, err := FindTailLineStartIndex(r, test.n)
   113  		if err != nil {
   114  			t.Error(err)
   115  		}
   116  		if s != test.start {
   117  			t.Errorf("%d != %d", s, test.start)
   118  		}
   119  	}
   120  }