gno.land/p/moul/x/wiki/v0⧉

1package wiki23import (4	"strings"5	"testing"67	"gno.land/p/nt/uassert/v0"8)910// render turns a diff into the compact "+a -b =c" form the tests assert on.11func render(lines []DiffLine) string {12	var b strings.Builder13	for _, l := range lines {14		switch l.Op {15		case OpInsert:16			b.WriteString("+")17		case OpDelete:18			b.WriteString("-")19		default:20			b.WriteString("=")21		}22		b.WriteString(l.Text)23		b.WriteString(";")24	}25	return b.String()26}2728func TestDiffLines(t *testing.T) {29	cases := []struct {30		name     string31		old, new string32		want     string33	}{34		{"identical", "a\nb\n", "a\nb\n", "=a;=b;"},35		{"append", "a\n", "a\nb\n", "=a;+b;"},36		{"prepend", "b\n", "a\nb\n", "+a;=b;"},37		{"delete", "a\nb\n", "a\n", "=a;-b;"},38		{"replace middle", "a\nb\nc\n", "a\nx\nc\n", "=a;-b;+x;=c;"},39		{"from empty", "", "a\n", "+a;"},40		{"to empty", "a\n", "", "-a;"},41		{"both empty", "", "", ""},42		{"no trailing newline", "a\nb", "a\nc", "=a;-b;+c;"},43	}44	for _, tc := range cases {45		got, exact := DiffLines(tc.old, tc.new)46		uassert.True(t, exact, tc.name+" must be exact")47		uassert.Equal(t, tc.want, render(got), tc.name)48	}49}5051func TestDiffStat(t *testing.T) {52	lines, _ := DiffLines("a\nb\nc\n", "a\nx\ny\nc\n")53	added, removed := DiffStat(lines)54	uassert.Equal(t, 2, added)55	uassert.Equal(t, 1, removed)56}5758// TestDiffCommonPrefixKeepsLongArticlesExact is the property that makes the59// DiffMaxLines bound usable in practice: a one-line edit to a 500-line article60// still diffs exactly, because only the changed region is fed to the LCS.61func TestDiffCommonPrefixKeepsLongArticlesExact(t *testing.T) {62	var b strings.Builder63	for i := 0; i < 500; i++ {64		b.WriteString("line\n")65	}66	old := b.String()67	updated := old + "added\n"6869	lines, exact := DiffLines(old, updated)70	uassert.True(t, exact, "a one-line change to a 500-line article must diff exactly")71	added, removed := DiffStat(lines)72	uassert.Equal(t, 1, added)73	uassert.Equal(t, 0, removed)74}7576// TestDiffDegradesInsteadOfBlowingTheGasBudget locks the documented fallback:77// past DiffMaxLines the diff becomes a block replacement rather than an78// unrenderable page.79func TestDiffDegradesInsteadOfBlowingTheGasBudget(t *testing.T) {80	var a, b strings.Builder81	for i := 0; i < DiffMaxLines+1; i++ {82		a.WriteString("old\n")83		b.WriteString("new\n")84	}85	lines, exact := DiffLines(a.String(), b.String())86	uassert.False(t, exact, "past the bound the diff must report itself inexact")87	added, removed := DiffStat(lines)88	uassert.Equal(t, DiffMaxLines+1, added)89	uassert.Equal(t, DiffMaxLines+1, removed)90}91