test: make cmd testable

compiler/internal/mockable/mockable.go

@@ -0,0 +1,29 @@
+package mockable
+
+import (
+	"os"
+)
+
+var (
+	exitFunc = os.Exit
+	exitCode int
+)
+
+// EnableMock enables mocking of os.Exit
+func EnableMock() {
+	exitCode = 0
+	exitFunc = func(code int) {
+		exitCode = code
+		panic("exit")
+	}
+}
+
+// Exit calls the current exit function
+func Exit(code int) {
+	exitFunc(code)
+}
+
+// ExitCode returns the last exit code from a mocked Exit call
+func ExitCode() int {
+	return exitCode
+}