Improved TestRowLoad tolerance for alternate pathing

TestRowLoad is fragile to pathing differences between the local
directory and test data when the local directory paths are shorter (in
runes). Fix this and a few other issues seen along the way.

row_test.go

@@ -12,6 +12,7 @@ import (
 	"strconv"
 	"strings"
 	"testing"
+	"unicode/utf8"
 
 	"9fans.net/go/plan9"
 	"9fans.net/go/plan9/client"
@@ -176,6 +177,7 @@ func TestRowLoad(t *testing.T) {
 
 // checkDump checks Edwood's current state (got) matches loaded dump file content (want).
 func checkDump(t *testing.T, got, want *dumpfile.Content) {
+	t.Helper()
 	// Ignore some mismatch. Positions may not match exactly.
 	// Window tags may get "Put" added or "Undo" removed, and
 	// because of the change in the tag, selection within the tag may not match.
@@ -188,6 +190,7 @@ func checkDump(t *testing.T, got, want *dumpfile.Content) {
 	}
 	for i, w := range want.Windows {
 		g := got.Windows[i]
+		t.Logf("[%d], %+v", i, g)
 		if math.Abs(g.Position-w.Position) < 10 {
 			g.Position = w.Position
 		}
@@ -208,6 +211,16 @@ func checkDump(t *testing.T, got, want *dumpfile.Content) {
 		if w := strings.Fields(g.Tag.Buffer); len(w) > 0 {
 			name = w[0]
 		}
+
+		// setTag1 (executed inside of Load) will (correctly) adjust the text
+		// selection to be within a valid range for the buffer.
+		if nr := utf8.RuneCountInString(g.Tag.Buffer); w.Tag.Q0 > nr {
+			w.Tag.Q0 = nr
+		}
+		if nr := utf8.RuneCountInString(g.Tag.Buffer); w.Tag.Q1 > nr {
+			w.Tag.Q1 = nr
+		}
+
 		if n := len(name); n > 0 && name[n-1] == filepath.Separator { // is directory
 			g.Tag.Q0 = w.Tag.Q0
 			g.Tag.Q1 = w.Tag.Q1

wind.go

@@ -123,7 +123,7 @@ func (w *Window) Init(clone *Window, r image.Rectangle, dis draw.Display) {
 		clonebuff := []rune(clone.tag.file.String())
 		w.tag.Insert(0, clonebuff, true)
 		w.tag.file.Reset()
-		w.tag.SetSelect(w.tag.file.Nbyte(), w.tag.file.Nbyte())
+		w.tag.SetSelect(w.tag.Nc(), w.tag.Nc())
 	}
 	r1 = r
 	r1.Min.Y += w.taglines*fontget(global.tagfont, w.display).Height() + 1
@@ -519,20 +519,20 @@ func (w *Window) setTag1() {
 		sb.WriteString(" ")
 	}
 
-	new := []rune(sb.String())
+	newtag := []rune(sb.String())
 
 	// replace tag if the new one is different
 	resize := false
-	if !runes.Equal(new, []rune(w.tag.file.String())) {
+	if !runes.Equal(newtag, []rune(w.tag.file.String())) {
 		resize = true // Might need to resize the tag
 		// try to preserve user selection
-		newbarIndex := runes.IndexRune(new, '|') // New always has '|'
+		newbarIndex := runes.IndexRune(newtag, '|') // New always has '|'
 		q0 := w.tag.q0
 		q1 := w.tag.q1
 
 		// These alter the Text's selection values.
 		w.tag.Delete(0, w.tag.Nc(), true)
-		w.tag.Insert(0, new, true)
+		w.tag.Insert(0, newtag, true)
 
 		// Rationalize the selection as best as possible
 		w.tag.q0 = util.Min(q0, w.tag.Nc())