app: add code for macOS and Windows apps under 'app' (#12933)

* app: add code for macOS and Windows apps under 'app'

* app: add readme

* app: windows and linux only for now

* ci: fix ui CI validation

---------

Co-authored-by: jmorganca <jmorganca@gmail.com>

app/logrotate/logrotate_test.go

@@ -0,0 +1,70 @@
+//go:build windows || darwin
+
+package logrotate
+
+import (
+	"os"
+	"path/filepath"
+	"strconv"
+	"testing"
+)
+
+func TestRotate(t *testing.T) {
+	logDir := t.TempDir()
+	logFile := filepath.Join(logDir, "testlog.log")
+
+	// No log exists
+	Rotate(logFile)
+
+	if err := os.WriteFile(logFile, []byte("1"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.Stat(logFile); os.IsNotExist(err) {
+		t.Fatal("expected log file to exist")
+	}
+
+	// First rotation
+	Rotate(logFile)
+	if _, err := os.Stat(filepath.Join(logDir, "testlog-1.log")); os.IsNotExist(err) {
+		t.Fatal("expected rotated log file to exist")
+	}
+	if _, err := os.Stat(filepath.Join(logDir, "testlog-2.log")); !os.IsNotExist(err) {
+		t.Fatal("expected no second rotated log file")
+	}
+	if _, err := os.Stat(logFile); !os.IsNotExist(err) {
+		t.Fatal("expected original log file to be moved")
+	}
+
+	// Should be a no-op without a new log
+	Rotate(logFile)
+	if _, err := os.Stat(filepath.Join(logDir, "testlog-1.log")); os.IsNotExist(err) {
+		t.Fatal("expected rotated log file to still exist")
+	}
+	if _, err := os.Stat(filepath.Join(logDir, "testlog-2.log")); !os.IsNotExist(err) {
+		t.Fatal("expected no second rotated log file")
+	}
+	if _, err := os.Stat(logFile); !os.IsNotExist(err) {
+		t.Fatal("expected no original log file")
+	}
+
+	for i := 2; i <= MaxLogFiles+1; i++ {
+		if err := os.WriteFile(logFile, []byte(strconv.Itoa(i)), 0o644); err != nil {
+			t.Fatal(err)
+		}
+		if _, err := os.Stat(logFile); os.IsNotExist(err) {
+			t.Fatal("expected log file to exist")
+		}
+		Rotate(logFile)
+		if _, err := os.Stat(logFile); !os.IsNotExist(err) {
+			t.Fatal("expected log file to be moved")
+		}
+		for j := 1; j < i; j++ {
+			if _, err := os.Stat(filepath.Join(logDir, "testlog-"+strconv.Itoa(j)+".log")); os.IsNotExist(err) {
+				t.Fatalf("expected rotated log file %d to exist", j)
+			}
+		}
+		if _, err := os.Stat(filepath.Join(logDir, "testlog-"+strconv.Itoa(i+1)+".log")); !os.IsNotExist(err) {
+			t.Fatalf("expected no rotated log file %d", i+1)
+		}
+	}
+}