Log errors in red in summary

filesystem.go

@@ -48,7 +48,7 @@ func (r operationRecord) summaryLine() (string, bool) {
 
 	status := "OK"
 	if r.err != nil {
-		status = fmt.Sprintf("FAIL: %v", r.err)
+		status = fmt.Sprintf("%sFAIL%s: %v", BRed, Reset, r.err)
 	} else if r.dryRun {
 		status = "DRY-RUN"
 	}

filesystem_test.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSummaryLineMarksFailuresInRed(t *testing.T) {
+	fs := NewRealFileSystem()
+
+	fs.RecordLinkAttempt(opSymlink, "/tmp/source", "/tmp/target", fmt.Errorf("boom"), false)
+
+	lines := fs.SummaryLines()
+	assert.Equal(t, 1, len(lines))
+	assert.Contains(t, lines[0], BRed+"FAIL"+Reset)
+	assert.Contains(t, lines[0], "boom")
+}