Merge 'bindings/rust: Return number of rows changed from Connection::execute()' from Rohith Suresh

Fixes #1904
This PR changes the existing behaviour of Connection.execute to not
return 0, but the number of rows that have been changed by the operation
within. The changes are:
1. Adds a getter for n_change and the execute function now returns the
n_change value
2. Integration test  to test the behaviour

Closes #1987

bindings/rust/src/lib.rs

@@ -312,7 +312,9 @@ impl Statement {
                     return Ok(2);
                 }
                 Ok(turso_core::StepResult::Done) => {
-                    return Ok(0);
+                    let changes = stmt.n_change();
+                    assert!(changes >= 0);
+                    return Ok(changes as u64);
                 }
                 Ok(turso_core::StepResult::IO) => {
                     let _ = stmt.run_once();

bindings/rust/tests/integration_tests.rs

@@ -115,3 +115,83 @@ async fn test_cacheflush() {
     fs::remove_file("test.db").await.unwrap();
     fs::remove_file("test.db-wal").await.unwrap();
 }
+
+#[tokio::test]
+async fn test_rows_returned() {
+    let db = Builder::new_local(":memory:").build().await.unwrap();
+    let conn = db.connect().unwrap();
+
+    //--- CRUD Operations ---//
+    conn.execute("CREATE TABLE t(id INTEGER PRIMARY KEY, val TEXT)", ())
+        .await
+        .unwrap();
+    let changed = conn
+        .execute("INSERT INTO t VALUES (1,'hello')", ())
+        .await
+        .unwrap();
+    let changed1 = conn
+        .execute("INSERT INTO t VALUES (2,'hi')", ())
+        .await
+        .unwrap();
+    let changed2 = conn
+        .execute("UPDATE t SET val='hi' WHERE id=1", ())
+        .await
+        .unwrap();
+    let changed3 = conn
+        .execute("DELETE FROM t WHERE val='hi'", ())
+        .await
+        .unwrap();
+    assert_eq!(changed, 1);
+    assert_eq!(changed1, 1);
+    assert_eq!(changed2, 1);
+    assert_eq!(changed3, 2);
+
+    //--- A more complicated example of insert with a select join subquery ---//
+    conn.execute(
+        "CREATE TABLE authors ( id INTEGER PRIMARY KEY, name TEXT NOT NULL);
+        ",
+        (),
+    )
+    .await
+    .unwrap();
+
+    conn.execute(
+        "CREATE TABLE books ( id INTEGER PRIMARY KEY, author_id INTEGER NOT NULL REFERENCES authors(id), title TEXT NOT NULL); "
+        ,()
+    ).await.unwrap();
+
+    conn.execute(
+        "CREATE TABLE prize_winners ( book_id INTEGER PRIMARY KEY, author_name TEXT NOT NULL);",
+        (),
+    )
+    .await
+    .unwrap();
+
+    conn.execute(
+        "INSERT INTO authors (id, name) VALUES (1, 'Alice'), (2, 'Bob');",
+        (),
+    )
+    .await
+    .unwrap();
+
+    conn.execute(
+        "INSERT INTO books (id, author_id, title) VALUES (1, 1, 'Rust in Action'), (2, 1, 'Async Adventures'), (3, 1, 'Fearless Concurrency'), (4, 1, 'Unsafe Tales'), (5, 1, 'Zero-Cost Futures'), (6, 2, 'Learning SQL');",
+        ()
+    ).await.unwrap();
+
+    let rows_changed = conn
+        .execute(
+            "
+        INSERT INTO prize_winners (book_id, author_name)
+        SELECT b.id, a.name
+        FROM   books b
+        JOIN   authors a ON a.id = b.author_id
+        WHERE  a.id = 1;       -- Alice’s five books
+        ",
+            (),
+        )
+        .await
+        .unwrap();
+
+    assert_eq!(rows_changed, 5);
+}