test: add pickFormat test for windows impl

Author: bemoty

cmd/client/cmd/clipboard_windows_test.go

@@ -0,0 +1,53 @@
+//go:build windows
+
+package cmd
+
+import "testing"
+
+func TestPickFormat(t *testing.T) {
+	tests := []struct {
+		name    string
+		formats []uint32
+		want    uint32
+	}{
+		{
+			name:    "prefers CF_PNG over all others",
+			formats: []uint32{cfUnicodeText, cfDIB, cfHdrop, cfPNG},
+			want:    cfPNG,
+		},
+		{
+			name:    "prefers CF_DIB over CF_HDROP and text",
+			formats: []uint32{cfUnicodeText, cfHdrop, cfDIB},
+			want:    cfDIB,
+		},
+		{
+			name:    "prefers CF_HDROP over text",
+			formats: []uint32{cfUnicodeText, cfHdrop},
+			want:    cfHdrop,
+		},
+		{
+			name:    "falls back to CF_UNICODETEXT",
+			formats: []uint32{cfUnicodeText},
+			want:    cfUnicodeText,
+		},
+		{
+			name:    "returns 0 for unknown formats",
+			formats: []uint32{42, 99},
+			want:    0,
+		},
+		{
+			name:    "empty list returns 0",
+			formats: []uint32{},
+			want:    0,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := pickFormat(tt.formats)
+			if got != tt.want {
+				t.Errorf("pickFormat(%v) = %d, want %d", tt.formats, got, tt.want)
+			}
+		})
+	}
+}