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// Copyright 2017, 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.md file.
package diff
import (
"fmt"
"math/rand"
"strings"
"testing"
"unicode"
)
func TestDifference(t *testing.T) {
tests := []struct {
// Before passing x and y to Difference, we strip all spaces so that
// they can be used by the test author to indicate a missing symbol
// in one of the lists.
x, y string
want string
}{{
x: "",
y: "",
want: "",
}, {
x: "#",
y: "#",
want: ".",
}, {
x: "##",
y: "# ",
want: ".X",
}, {
x: "a#",
y: "A ",
want: "MX",
}, {
x: "#a",
y: " A",
want: "XM",
}, {
x: "# ",
y: "##",
want: ".Y",
}, {
x: " #",
y: "@#",
want: "Y.",
}, {
x: "@#",
y: " #",
want: "X.",
}, {
x: "##########0123456789",
y: " 0123456789",
want: "XXXXXXXXXX..........",
}, {
x: " 0123456789",
y: "##########0123456789",
want: "YYYYYYYYYY..........",
}, {
x: "#####0123456789#####",
y: " 0123456789 ",
want: "XXXXX..........XXXXX",
}, {
x: " 0123456789 ",
y: "#####0123456789#####",
want: "YYYYY..........YYYYY",
}, {
x: "01234##########56789",
y: "01234 56789",
want: ".....XXXXXXXXXX.....",
}, {
x: "01234 56789",
y: "01234##########56789",
want: ".....YYYYYYYYYY.....",
}, {
x: "0123456789##########",
y: "0123456789 ",
want: "..........XXXXXXXXXX",
}, {
x: "0123456789 ",
y: "0123456789##########",
want: "..........YYYYYYYYYY",
}, {
x: "abcdefghij0123456789",
y: "ABCDEFGHIJ0123456789",
want: "MMMMMMMMMM..........",
}, {
x: "ABCDEFGHIJ0123456789",
y: "abcdefghij0123456789",
want: "MMMMMMMMMM..........",
}, {
x: "01234abcdefghij56789",
y: "01234ABCDEFGHIJ56789",
want: ".....MMMMMMMMMM.....",
}, {
x: "01234ABCDEFGHIJ56789",
y: "01234abcdefghij56789",
want: ".....MMMMMMMMMM.....",
}, {
x: "0123456789abcdefghij",
y: "0123456789ABCDEFGHIJ",
want: "..........MMMMMMMMMM",
}, {
x: "0123456789ABCDEFGHIJ",
y: "0123456789abcdefghij",
want: "..........MMMMMMMMMM",
}, {
x: "ABCDEFGHIJ0123456789 ",
y: " 0123456789abcdefghij",
want: "XXXXXXXXXX..........YYYYYYYYYY",
}, {
x: " 0123456789abcdefghij",
y: "ABCDEFGHIJ0123456789 ",
want: "YYYYYYYYYY..........XXXXXXXXXX",
}, {
x: "ABCDE0123456789 FGHIJ",
y: " 0123456789abcdefghij",
want: "XXXXX..........YYYYYMMMMM",
}, {
x: " 0123456789abcdefghij",
y: "ABCDE0123456789 FGHIJ",
want: "YYYYY..........XXXXXMMMMM",
}, {
x: "ABCDE01234F G H I J 56789 ",
y: " 01234 a b c d e56789fghij",
want: "XXXXX.....XYXYXYXYXY.....YYYYY",
}, {
x: " 01234a b c d e 56789fghij",
y: "ABCDE01234 F G H I J56789 ",
want: "YYYYY.....XYXYXYXYXY.....XXXXX",
}, {
x: "FGHIJ01234ABCDE56789 ",
y: " 01234abcde56789fghij",
want: "XXXXX.....MMMMM.....YYYYY",
}, {
x: " 01234abcde56789fghij",
y: "FGHIJ01234ABCDE56789 ",
want: "YYYYY.....MMMMM.....XXXXX",
}, {
x: "ABCAB BA ",
y: " C BABAC",
want: "XX.X.Y..Y",
}, {
x: "# #### ###",
y: "#y####yy###",
want: ".Y....YY...",
}, {
x: "# #### # ##x#x",
y: "#y####y y## # ",
want: ".Y....YXY..X.X",
}, {
x: "###z#z###### x #",
y: "#y##Z#Z###### yy#",
want: ".Y..M.M......XYY.",
}, {
x: "0 12z3x 456789 x x 0",
y: "0y12Z3 y456789y y y0",
want: ".Y..M.XY......YXYXY.",
}, {
x: "0 2 4 6 8 ..................abXXcdEXF.ghXi",
y: " 1 3 5 7 9..................AB CDE F.GH I",
want: "XYXYXYXYXY..................MMXXMM.X..MMXM",
}, {
x: "I HG.F EDC BA..................9 7 5 3 1 ",
y: "iXhg.FXEdcXXba.................. 8 6 4 2 0",
want: "MYMM..Y.MMYYMM..................XYXYXYXYXY",
}, {
x: "x1234",
y: " 1234",
want: "X....",
}, {
x: "x123x4",
y: " 123 4",
want: "X...X.",
}, {
x: "x1234x56",
y: " 1234 ",
want: "X....XXX",
}, {
x: "x1234xxx56",
y: " 1234 56",
want: "X....XXX..",
}, {
x: ".1234...ab",
y: " 1234 AB",
want: "X....XXXMM",
}, {
x: "x1234xxab.",
y: " 1234 AB ",
want: "X....XXMMX",
}, {
x: " 0123456789",
y: "9012345678 ",
want: "Y.........X",
}, {
x: " 0123456789",
y: "8901234567 ",
want: "YY........XX",
}, {
x: " 0123456789",
y: "7890123456 ",
want: "YYY.......XXX",
}, {
x: " 0123456789",
y: "6789012345 ",
want: "YYYY......XXXX",
}, {
x: "0123456789 ",
y: " 5678901234",
want: "XXXXX.....YYYYY",
}, {
x: "0123456789 ",
y: " 4567890123",
want: "XXXX......YYYY",
}, {
x: "0123456789 ",
y: " 3456789012",
want: "XXX.......YYY",
}, {
x: "0123456789 ",
y: " 2345678901",
want: "XX........YY",
}, {
x: "0123456789 ",
y: " 1234567890",
want: "X.........Y",
}, {
x: "0 1 2 3 45 6 7 8 9 ",
y: " 9 8 7 6 54 3 2 1 0",
want: "XYXYXYXYX.YXYXYXYXY",
}, {
x: "0 1 2345678 9 ",
y: " 6 72 5 819034",
want: "XYXY.XX.XX.Y.YYY",
}, {
x: "F B Q M O I G T L N72X90 E 4S P 651HKRJU DA 83CVZW",
y: " 5 W H XO10R9IV K ZLCTAJ8P3N SEQM4 7 2G6 UBD F ",
want: "XYXYXYXY.YYYY.YXYXY.YYYYYYY.XXXXXY.YY.XYXYY.XXXXXX.Y.XYXXXXXX",
}}
for _, tt := range tests {
t.Run("", func(t *testing.T) {
x := strings.Replace(tt.x, " ", "", -1)
y := strings.Replace(tt.y, " ", "", -1)
es := testStrings(t, x, y)
if got := es.String(); got != tt.want {
t.Errorf("Difference(%s, %s):\ngot %s\nwant %s", x, y, got, tt.want)
}
})
}
}
func TestDifferenceFuzz(t *testing.T) {
tests := []struct{ px, py, pm float32 }{
{px: 0.0, py: 0.0, pm: 0.1},
{px: 0.0, py: 0.1, pm: 0.0},
{px: 0.1, py: 0.0, pm: 0.0},
{px: 0.0, py: 0.1, pm: 0.1},
{px: 0.1, py: 0.0, pm: 0.1},
{px: 0.2, py: 0.2, pm: 0.2},
{px: 0.3, py: 0.1, pm: 0.2},
{px: 0.1, py: 0.3, pm: 0.2},
{px: 0.2, py: 0.2, pm: 0.2},
{px: 0.3, py: 0.3, pm: 0.3},
{px: 0.1, py: 0.1, pm: 0.5},
{px: 0.4, py: 0.1, pm: 0.5},
{px: 0.3, py: 0.2, pm: 0.5},
{px: 0.2, py: 0.3, pm: 0.5},
{px: 0.1, py: 0.4, pm: 0.5},
}
for i, tt := range tests {
t.Run(fmt.Sprintf("P%d", i), func(t *testing.T) {
// Sweep from 1B to 1KiB.
for n := 1; n <= 1024; n <<= 1 {
t.Run(fmt.Sprintf("N%d", n), func(t *testing.T) {
for j := 0; j < 10; j++ {
x, y := generateStrings(n, tt.px, tt.py, tt.pm, int64(j))
testStrings(t, x, y)
}
})
}
})
}
}
func BenchmarkDifference(b *testing.B) {
for n := 1 << 10; n <= 1<<20; n <<= 2 {
b.Run(fmt.Sprintf("N%d", n), func(b *testing.B) {
x, y := generateStrings(n, 0.05, 0.05, 0.10, 0)
b.ReportAllocs()
b.SetBytes(int64(len(x) + len(y)))
for i := 0; i < b.N; i++ {
Difference(len(x), len(y), func(ix, iy int) Result {
return compareByte(x[ix], y[iy])
})
}
})
}
}
func generateStrings(n int, px, py, pm float32, seed int64) (string, string) {
if px+py+pm > 1.0 {
panic("invalid probabilities")
}
py += px
pm += py
b := make([]byte, n)
r := rand.New(rand.NewSource(seed))
r.Read(b)
var x, y []byte
for len(b) > 0 {
switch p := r.Float32(); {
case p < px: // UniqueX
x = append(x, b[0])
case p < py: // UniqueY
y = append(y, b[0])
case p < pm: // Modified
x = append(x, 'A'+(b[0]%26))
y = append(y, 'a'+(b[0]%26))
default: // Identity
x = append(x, b[0])
y = append(y, b[0])
}
b = b[1:]
}
return string(x), string(y)
}
func testStrings(t *testing.T, x, y string) EditScript {
es := Difference(len(x), len(y), func(ix, iy int) Result {
return compareByte(x[ix], y[iy])
})
if es.LenX() != len(x) {
t.Errorf("es.LenX = %d, want %d", es.LenX(), len(x))
}
if es.LenY() != len(y) {
t.Errorf("es.LenY = %d, want %d", es.LenY(), len(y))
}
if !validateScript(x, y, es) {
t.Errorf("invalid edit script: %v", es)
}
return es
}
func validateScript(x, y string, es EditScript) bool {
var bx, by []byte
for _, e := range es {
switch e {
case Identity:
if !compareByte(x[len(bx)], y[len(by)]).Equal() {
return false
}
bx = append(bx, x[len(bx)])
by = append(by, y[len(by)])
case UniqueX:
bx = append(bx, x[len(bx)])
case UniqueY:
by = append(by, y[len(by)])
case Modified:
if !compareByte(x[len(bx)], y[len(by)]).Similar() {
return false
}
bx = append(bx, x[len(bx)])
by = append(by, y[len(by)])
}
}
return string(bx) == x && string(by) == y
}
// compareByte returns a Result where the result is Equal if x == y,
// similar if x and y differ only in casing, and different otherwise.
func compareByte(x, y byte) (r Result) {
switch {
case x == y:
return equalResult // Identity
case unicode.ToUpper(rune(x)) == unicode.ToUpper(rune(y)):
return similarResult // Modified
default:
return differentResult // UniqueX or UniqueY
}
}
var (
equalResult = Result{NDiff: 0}
similarResult = Result{NDiff: 1}
differentResult = Result{NDiff: 2}
)
func TestResult(t *testing.T) {
tests := []struct {
result Result
wantEqual bool
wantSimilar bool
}{
// equalResult is equal since NDiff == 0, by definition of Equal method.
{equalResult, true, true},
// similarResult is similar since it is a binary result where only one
// element was compared (i.e., Either NSame==1 or NDiff==1).
{similarResult, false, true},
// differentResult is different since there are enough differences that
// it isn't even considered similar.
{differentResult, false, false},
// Zero value is always equal.
{Result{NSame: 0, NDiff: 0}, true, true},
// Binary comparisons (where NSame+NDiff == 1) are always similar.
{Result{NSame: 1, NDiff: 0}, true, true},
{Result{NSame: 0, NDiff: 1}, false, true},
// More complex ratios. The exact ratio for similarity may change,
// and may require updates to these test cases.
{Result{NSame: 1, NDiff: 1}, false, true},
{Result{NSame: 1, NDiff: 2}, false, true},
{Result{NSame: 1, NDiff: 3}, false, false},
{Result{NSame: 2, NDiff: 1}, false, true},
{Result{NSame: 2, NDiff: 2}, false, true},
{Result{NSame: 2, NDiff: 3}, false, true},
{Result{NSame: 3, NDiff: 1}, false, true},
{Result{NSame: 3, NDiff: 2}, false, true},
{Result{NSame: 3, NDiff: 3}, false, true},
{Result{NSame: 1000, NDiff: 0}, true, true},
{Result{NSame: 1000, NDiff: 1}, false, true},
{Result{NSame: 1000, NDiff: 2}, false, true},
{Result{NSame: 0, NDiff: 1000}, false, false},
{Result{NSame: 1, NDiff: 1000}, false, false},
{Result{NSame: 2, NDiff: 1000}, false, false},
}
for _, tt := range tests {
if got := tt.result.Equal(); got != tt.wantEqual {
t.Errorf("%#v.Equal() = %v, want %v", tt.result, got, tt.wantEqual)
}
if got := tt.result.Similar(); got != tt.wantSimilar {
t.Errorf("%#v.Similar() = %v, want %v", tt.result, got, tt.wantSimilar)
}
}
}