1 files changed, 119 insertions, 0 deletions
diff --git a/src/strings/compare_test.go b/src/strings/compare_test.go
new file mode 100644
index 0000000..a435784
--- /dev/null
+++ b/src/strings/compare_test.go
@@ -0,0 +1,119 @@
+// 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 (
+	"internal/testenv"
+	. "strings"
+	"testing"
+	"unsafe"
+)
+
+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) {
+	// unsafeString converts a []byte to a string with no allocation.
+	// The caller must not modify b while the result string is in use.
+	unsafeString := func(b []byte) string {
+		return unsafe.String(unsafe.SliceData(b), len(b))
+	}
+
+	lengths := make([]int, 0) // lengths to test in ascending order
+	for i := 0; i <= 128; i++ {
+		lengths = append(lengths, i)
+	}
+	lengths = append(lengths, 256, 512, 1024, 1333, 4095, 4096, 4097)
+
+	if !testing.Short() || testenv.Builder() != "" {
+		lengths = append(lengths, 65535, 65536, 65537, 99999)
+	}
+
+	n := lengths[len(lengths)-1]
+	a := make([]byte, n+1)
+	b := make([]byte, n+1)
+	lastLen := 0
+	for _, len := range lengths {
+		// 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
+		}
+
+		sa, sb := unsafeString(a), unsafeString(b)
+		cmp := Compare(sa[:len], sb[:len])
+		if cmp != 0 {
+			t.Errorf(`CompareIdentical(%d) = %d`, len, cmp)
+		}
+		if len > 0 {
+			cmp = Compare(sa[:len-1], sb[:len])
+			if cmp != -1 {
+				t.Errorf(`CompareAshorter(%d) = %d`, len, cmp)
+			}
+			cmp = Compare(sa[:len], sb[:len-1])
+			if cmp != 1 {
+				t.Errorf(`CompareBshorter(%d) = %d`, len, cmp)
+			}
+		}
+		for k := lastLen; k < len; k++ {
+			b[k] = a[k] - 1
+			cmp = Compare(unsafeString(a[:len]), unsafeString(b[:len]))
+			if cmp != 1 {
+				t.Errorf(`CompareAbigger(%d,%d) = %d`, len, k, cmp)
+			}
+			b[k] = a[k] + 1
+			cmp = Compare(unsafeString(a[:len]), unsafeString(b[:len]))
+			if cmp != -1 {
+				t.Errorf(`CompareBbigger(%d,%d) = %d`, len, k, cmp)
+			}
+			b[k] = a[k]
+		}
+		lastLen = len
+	}
+}