Update api doc for java, nodejs, python and add pytest for in-mem mode

src/include/main/database.h

@@ -91,7 +91,8 @@ class Database {
 public:
     /**
      * @brief Creates a database object.
-     * @param databasePath Database path.
+     * @param databasePath Database path. If the path is empty, or equal to `:memory:`, the database
+     * will be created in memory.
      * @param systemConfig System configurations (buffer pool size and max num threads).
      */
     KUZU_API explicit Database(std::string_view databasePath,

tools/java_api/src/main/java/com/kuzudb/KuzuDatabase.java

@@ -12,6 +12,13 @@ public class KuzuDatabase {
     boolean destroyed = false;
     boolean readOnly = false;
 
+    /**
+     * Creates a database object. The database will be created in memory with default settings.
+     */
+    public KuzuDatabase() {
+        this("");
+    }
+
     /**
      * Creates a database object.
      * @param databasePath: Database path. If the database does not already exist, it will be created.
@@ -25,7 +32,8 @@ public KuzuDatabase(String databasePath) {
 
     /**
     * Creates a database object.
-    * @param databasePath: Database path. If the database does not already exist, it will be created.
+    * @param databasePath: Database path. If the path is empty, or equal to `:memory:`, the database will be created in
+    * memory.
     * @param bufferPoolSize: Max size of the buffer pool in bytes.
     * @param enableCompression: Enable compression in storage.
     * @param readOnly: Open the database in READ_ONLY mode.

tools/java_api/src/test/java/com/kuzudb/test/DatabaseTest.java

@@ -41,4 +41,14 @@ void DBCreationAndDestroyWithPathOnly() {
             fail("DBCreationAndDestroyWithPathOnly failed");
         }
     }
+
+    @Test
+    void DBCreationAndDestroyWithNoParam(){
+        try {
+            KuzuDatabase database = new KuzuDatabase();
+            database.destroy();
+        } catch (Exception e) {
+            fail("DBCreationAndDestroyWithNoParam failed");
+        }
+    }
 }

tools/nodejs_api/src_js/database.js

@@ -10,7 +10,8 @@ class Database {
    * executed. To initialize the database immediately, call the `init()`
    * function on the returned object.
    *
-   * @param {String} databasePath path to the database file.
+   * @param {String} databasePath path to the database file. If the path is not specified, or empty, or equal to
+   `:memory:`, the database will be created in memory.
    * @param {Number} bufferManagerSize size of the buffer manager in bytes.
    * @param {Boolean} enableCompression whether to enable compression.
    * @param {Boolean} readOnly if true, database will be opened in read-only mode.
@@ -19,13 +20,16 @@ class Database {
    * address space limit some environment.
    */
   constructor(
-    databasePath = "",
+    databasePath,
     bufferManagerSize = 0,
     enableCompression = true,
     readOnly = false,
     maxDBSize = 0
   ) {
-    if (typeof databasePath !== "string") {
+    if (!databasePath) {
+      databasePath = ":memory:";
+    }
+    else if (typeof databasePath !== "string") {
       throw new Error("Database path must be a string.");
     }
     if (typeof bufferManagerSize !== "number" || bufferManagerSize < 0) {

tools/nodejs_api/test/test_database.js

@@ -189,6 +189,48 @@ describe("Database constructor", function () {
       assert.equal(e.message, "Max DB size must be a positive integer.");
     }
   });
+
+  it("should create an in-memory database when no path is provided", async function () {
+    const testDb = new kuzu.Database();
+    const conn = new kuzu.Connection(testDb);
+    let res = await conn.query("CREATE NODE TABLE person(name STRING, age INT64, PRIMARY KEY(name));"); 
+    res.close();
+    res = await conn.query("CREATE (:person {name: 'Alice', age: 30});");
+    res.close();
+    res = await conn.query("CREATE (:person {name: 'Bob', age: 40});");
+    res.close();
+    res = await conn.query("MATCH (p:person) RETURN p.*;");
+    const result = await res.getAll();
+    assert.equal(result.length, 2);
+    assert.deepEqual(result, [
+      { 'p.name': 'Alice', 'p.age': 30 },
+      { 'p.name': 'Bob', 'p.age': 40 }
+    ]);
+    res.close();
+    conn.close();
+    testDb.close();
+  });
+
+  it("should create an in-memory database when empty path is provided", async function () {
+    const testDb = new kuzu.Database("", 1 << 28 /* 256MB */);
+    const conn = new kuzu.Connection(testDb);
+    let res = await conn.query("CREATE NODE TABLE person(name STRING, age INT64, PRIMARY KEY(name));");
+    res.close();
+    res = await conn.query("CREATE (:person {name: 'Alice', age: 30});");
+    res.close();
+    res = await conn.query("CREATE (:person {name: 'Bob', age: 40});");
+    res.close();
+    res = await conn.query("MATCH (p:person) RETURN p.*;");
+    const result = await res.getAll();
+    assert.equal(result.length, 2);
+    assert.deepEqual(result, [
+      { 'p.name': 'Alice', 'p.age': 30 },
+      { 'p.name': 'Bob', 'p.age': 40 }
+    ]);
+    res.close();
+    conn.close();
+    testDb.close();
+  });
 });
 
 describe("Database close", function () {

tools/python_api/src_py/database.py

@@ -27,7 +27,7 @@ class Database:
 
     def __init__(
         self,
-        database_path: str | Path = "",
+        database_path: str | Path | None = None,
         *,
         buffer_pool_size: int = 0,
         max_num_threads: int = 0,
@@ -40,7 +40,8 @@ def __init__(
         Parameters
         ----------
         database_path : str, Path
-            The path to database files
+            The path to database files. If the path is not specified, or empty, or equal to `:memory:`, the database
+            will be created in memory.
 
         buffer_pool_size : int
             The maximum size of buffer pool in bytes. Defaults to ~80% of system memory.
@@ -73,6 +74,8 @@ def __init__(
              environment and 1GB under 32-bit one.
 
         """
+        if database_path is None:
+            database_path = ":memory:"
         if isinstance(database_path, Path):
             database_path = str(database_path)
 

tools/python_api/test/test_database.py

@@ -77,3 +77,45 @@ def test_database_context_manager(tmp_path: Path, build_dir: Path) -> None:
     # TODO: Enable this test on Windows when the read-only mode is implemented.
     if sys.platform != "win32":
         open_database_on_subprocess(db_path, build_dir)
+
+
+def test_in_mem_database_memory_db_path() -> None:
+        db = kuzu.Database(database_path=":memory:")
+        assert not db.is_closed
+        assert db._database is not None
+
+        # Open the database on a subprocess. It should raise an exception.
+        conn = kuzu.Connection(db)
+        conn.execute("CREATE NODE TABLE person(name STRING, age INT64, PRIMARY KEY(name));")
+        conn.execute("CREATE (:person {name: 'Alice', age: 30});")
+        conn.execute("CREATE (:person {name: 'Bob', age: 40});")
+        result = conn.execute("MATCH (p:person) RETURN p.*")
+        assert result.get_num_tuples() == 2
+
+
+def test_in_mem_database_empty_db_path() -> None:
+        db = kuzu.Database()
+        assert not db.is_closed
+        assert db._database is not None
+
+        # Open the database on a subprocess. It should raise an exception.
+        conn = kuzu.Connection(db)
+        conn.execute("CREATE NODE TABLE person(name STRING, age INT64, PRIMARY KEY(name));")
+        conn.execute("CREATE (:person {name: 'Alice', age: 30});")
+        conn.execute("CREATE (:person {name: 'Bob', age: 40});")
+        result = conn.execute("MATCH (p:person) RETURN p.*")
+        assert result.get_num_tuples() == 2
+
+
+def test_in_mem_database_no_db_path() -> None:
+    with kuzu.Database(database_path="") as db:
+        assert not db.is_closed
+        assert db._database is not None
+
+        # Open the database on a subprocess. It should raise an exception.
+        conn = kuzu.Connection(db)
+        conn.execute("CREATE NODE TABLE person(name STRING, age INT64, PRIMARY KEY(name));")
+        conn.execute("CREATE (:person {name: 'Alice', age: 30});")
+        conn.execute("CREATE (:person {name: 'Bob', age: 40});")
+        with conn.execute("MATCH (p:person) RETURN p.*") as result:
+            assert result.get_num_tuples() == 2