Update merge to also take single records (#6919)

crates/nu-command/tests/commands/merge.rs

@@ -38,5 +38,89 @@ fn row() {
         ));
 
         assert_eq!(actual.out, "2");
-    })
+    });
+}
+
+#[test]
+fn single_record_no_overwrite() {
+    assert_eq!(
+        nu!(
+            cwd: ".", pipeline(
+            r#"
+            {a: 1, b: 5} | merge {c: 2} | to nuon
+            "#
+        ))
+        .out,
+        "{a: 1, b: 5, c: 2}"
+    );
+}
+
+#[test]
+fn single_record_overwrite() {
+    assert_eq!(
+        nu!(
+            cwd: ".", pipeline(
+            r#"
+            {a: 1, b: 2} | merge {a: 2} | to nuon
+            "#
+        ))
+        .out,
+        "{a: 2, b: 2}"
+    );
+}
+
+#[test]
+fn single_row_table_overwrite() {
+    assert_eq!(
+        nu!(
+            cwd: ".", pipeline(
+            r#"
+            [[a b]; [1 4]] | merge [[a b]; [2 4]] | to nuon
+            "#
+        ))
+        .out,
+        "[[a, b]; [2, 4]]"
+    );
+}
+
+#[test]
+fn single_row_table_no_overwrite() {
+    assert_eq!(
+        nu!(
+            cwd: ".", pipeline(
+            r#"
+            [[a b]; [1 4]] | merge [[c d]; [2 4]] | to nuon
+            "#
+        ))
+        .out,
+        "[[a, b, c, d]; [1, 4, 2, 4]]"
+    );
+}
+
+#[test]
+fn multi_row_table_no_overwrite() {
+    assert_eq!(
+        nu!(
+            cwd: ".", pipeline(
+            r#"
+            [[a b]; [1 4] [8 9] [9 9]] | merge [[c d]; [2 4]]  | to nuon
+            "#
+        ))
+        .out,
+        "[{a: 1, b: 4, c: 2, d: 4}, {a: 8, b: 9}, {a: 9, b: 9}]"
+    );
+}
+
+#[test]
+fn multi_row_table_overwrite() {
+    assert_eq!(
+        nu!(
+            cwd: ".", pipeline(
+            r#"
+            [[a b]; [1 4] [8 9] [9 9]] | merge  [[a b]; [7 7]]  | to nuon
+            "#
+        ))
+        .out,
+        "[[a, b]; [7, 7], [8, 9], [9, 9]]"
+    );
 }