Fix panic when terminal width is 0

testjson/dotformat.go

@@ -70,8 +70,7 @@ func (l *dotLine) checkWidth(prefix, terminal int) {
 func newDotFormatter(out io.Writer) EventFormatter {
 	w, _, err := terminal.GetSize(int(os.Stdout.Fd()))
 	if err != nil || w == 0 {
-		logrus.Warn(err.Error())
-		logrus.Warn("Failed to detect terminal width for dots format.")
+		logrus.Warnf("Failed to detect terminal width for dots format, error: %v", err)
 		return &formatAdapter{format: dotsFormatV1, out: out}
 	}
 	return &dotFormatter{

testjson/dotformat_test.go

@@ -12,11 +12,11 @@ import (
 	"time"
 	"unicode/utf8"
 
-	"gotest.tools/gotestsum/internal/dotwriter"
-
 	"gotest.tools/assert"
 	"gotest.tools/assert/cmp"
 	"gotest.tools/golden"
+	"gotest.tools/gotestsum/internal/dotwriter"
+	"gotest.tools/skip"
 )
 
 func TestScanTestOutput_WithDotsFormatter(t *testing.T) {
@@ -152,3 +152,12 @@ func TestFmtDotElapsed_RuneCountProperty(t *testing.T) {
 		Rand:          rand.New(rand.NewSource(seed)),
 	}))
 }
+
+func TestNewDotFormatter(t *testing.T) {
+	buf := new(bytes.Buffer)
+	ef := newDotFormatter(buf)
+
+	d, ok := ef.(*dotFormatter)
+	skip.If(t, !ok, "no terminal width")
+	assert.Assert(t, d.termWidth != 0)
+}