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Source file src/strings/compare_test.go

Documentation: strings

  // Copyright 2013 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  package strings_test
  
  // Derived from bytes/compare_test.go.
  // Benchmarks omitted since the underlying implementation is identical.
  
  import (
  	. "strings"
  	"testing"
  )
  
  var compareTests = []struct {
  	a, b string
  	i    int
  }{
  	{"", "", 0},
  	{"a", "", 1},
  	{"", "a", -1},
  	{"abc", "abc", 0},
  	{"ab", "abc", -1},
  	{"abc", "ab", 1},
  	{"x", "ab", 1},
  	{"ab", "x", -1},
  	{"x", "a", 1},
  	{"b", "x", -1},
  	// test runtime·memeq's chunked implementation
  	{"abcdefgh", "abcdefgh", 0},
  	{"abcdefghi", "abcdefghi", 0},
  	{"abcdefghi", "abcdefghj", -1},
  }
  
  func TestCompare(t *testing.T) {
  	for _, tt := range compareTests {
  		cmp := Compare(tt.a, tt.b)
  		if cmp != tt.i {
  			t.Errorf(`Compare(%q, %q) = %v`, tt.a, tt.b, cmp)
  		}
  	}
  }
  
  func TestCompareIdenticalString(t *testing.T) {
  	var s = "Hello Gophers!"
  	if Compare(s, s) != 0 {
  		t.Error("s != s")
  	}
  	if Compare(s, s[:1]) != 1 {
  		t.Error("s > s[:1] failed")
  	}
  }
  
  func TestCompareStrings(t *testing.T) {
  	n := 128
  	a := make([]byte, n+1)
  	b := make([]byte, n+1)
  	for len := 0; len < 128; len++ {
  		// randomish but deterministic data. No 0 or 255.
  		for i := 0; i < len; i++ {
  			a[i] = byte(1 + 31*i%254)
  			b[i] = byte(1 + 31*i%254)
  		}
  		// data past the end is different
  		for i := len; i <= n; i++ {
  			a[i] = 8
  			b[i] = 9
  		}
  
  		cmp := Compare(string(a[:len]), string(b[:len]))
  		if cmp != 0 {
  			t.Errorf(`CompareIdentical(%d) = %d`, len, cmp)
  		}
  		if len > 0 {
  			cmp = Compare(string(a[:len-1]), string(b[:len]))
  			if cmp != -1 {
  				t.Errorf(`CompareAshorter(%d) = %d`, len, cmp)
  			}
  			cmp = Compare(string(a[:len]), string(b[:len-1]))
  			if cmp != 1 {
  				t.Errorf(`CompareBshorter(%d) = %d`, len, cmp)
  			}
  		}
  		for k := 0; k < len; k++ {
  			b[k] = a[k] - 1
  			cmp = Compare(string(a[:len]), string(b[:len]))
  			if cmp != 1 {
  				t.Errorf(`CompareAbigger(%d,%d) = %d`, len, k, cmp)
  			}
  			b[k] = a[k] + 1
  			cmp = Compare(string(a[:len]), string(b[:len]))
  			if cmp != -1 {
  				t.Errorf(`CompareBbigger(%d,%d) = %d`, len, k, cmp)
  			}
  			b[k] = a[k]
  		}
  	}
  }
  

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