Add tests

tests/by-util/test_lsmem.rs

@@ -10,6 +10,15 @@ fn test_invalid_arg() {
     new_ucmd!().arg("--definitely-invalid").fails().code_is(1);
 }
 
+#[test]
+fn test_basic() {
+    // Verify basic usage with no args prints both table and summary
+    new_ucmd!()
+        .succeeds()
+        .stdout_contains("STATE REMOVABLE")
+        .stdout_contains("Memory block size:");
+}
+
 #[test]
 fn test_table_not_padded() {
     let result = new_ucmd!().succeeds();
@@ -19,3 +28,11 @@ fn test_table_not_padded() {
         "Table output should not start with a space"
     );
 }
+
+#[test]
+fn test_json_output() {
+    new_ucmd!()
+        .arg("-J")
+        .succeeds()
+        .stdout_contains("   \"memory\": [\n");
+}