diff --git a/kclvm/ast_pretty/src/lib.rs b/kclvm/ast_pretty/src/lib.rs
index 980ba8550..ab5973b04 100644
--- a/kclvm/ast_pretty/src/lib.rs
+++ b/kclvm/ast_pretty/src/lib.rs
@@ -261,7 +261,7 @@ impl<'p> Printer<'p> {
     }
 }
 
-/// Print AST to string
+/// Print AST to string. The default format is according to the KCL code style defined here: https://kcl-lang.io/docs/reference/lang/spec/codestyle
 pub fn print_ast_module(module: &Module) -> String {
     let mut printer = Printer::default();
     printer.write_module(module);
diff --git a/kclvm/tools/src/format/test_data/format_data/different_stmts_line_breaks.golden b/kclvm/tools/src/format/test_data/format_data/different_stmts_line_breaks.golden
new file mode 100644
index 000000000..1dc12573c
--- /dev/null
+++ b/kclvm/tools/src/format/test_data/format_data/different_stmts_line_breaks.golden
@@ -0,0 +1,8 @@
+import a
+
+schema A:
+    name: str = a.name
+
+A {}
+
+# Break one blank line between different statements e.g., import, schema and expression statements.
diff --git a/kclvm/tools/src/format/test_data/format_data/different_stmts_line_breaks.input b/kclvm/tools/src/format/test_data/format_data/different_stmts_line_breaks.input
new file mode 100644
index 000000000..92b107a1e
--- /dev/null
+++ b/kclvm/tools/src/format/test_data/format_data/different_stmts_line_breaks.input
@@ -0,0 +1,6 @@
+import a
+schema A:
+    name: str = a.name
+A{}
+
+# Break one blank line between different statements e.g., import, schema and expression statements.
diff --git a/kclvm/tools/src/format/test_data/format_data/list_dict_schema_expr.golden b/kclvm/tools/src/format/test_data/format_data/list_dict_schema_expr.golden
new file mode 100644
index 000000000..a71205411
--- /dev/null
+++ b/kclvm/tools/src/format/test_data/format_data/list_dict_schema_expr.golden
@@ -0,0 +1,20 @@
+dict = {
+    "key": "value"
+}
+
+dict2 = {"key": "value"}
+
+list = [
+    first
+    second
+]
+
+list2 = [first, second]
+
+expr = Person {
+    name: "Alice"
+}
+
+expr2 = Person {name: "Alice"}
+
+# It's both acceptable to write each entry in the list/dict/schema expr without line breaks, or separate each entry with one line break.
diff --git a/kclvm/tools/src/format/test_data/format_data/list_dict_schema_expr.input b/kclvm/tools/src/format/test_data/format_data/list_dict_schema_expr.input
new file mode 100644
index 000000000..a71205411
--- /dev/null
+++ b/kclvm/tools/src/format/test_data/format_data/list_dict_schema_expr.input
@@ -0,0 +1,20 @@
+dict = {
+    "key": "value"
+}
+
+dict2 = {"key": "value"}
+
+list = [
+    first
+    second
+]
+
+list2 = [first, second]
+
+expr = Person {
+    name: "Alice"
+}
+
+expr2 = Person {name: "Alice"}
+
+# It's both acceptable to write each entry in the list/dict/schema expr without line breaks, or separate each entry with one line break.
diff --git a/kclvm/tools/src/format/test_data/format_data/union_types.golden b/kclvm/tools/src/format/test_data/format_data/union_types.golden
new file mode 100644
index 000000000..86f5bc5d7
--- /dev/null
+++ b/kclvm/tools/src/format/test_data/format_data/union_types.golden
@@ -0,0 +1,5 @@
+workloadType: "Deployment" | "StatefulSet" = "Deployment"
+ServiceType: "LoadBalance" | "ClusterIP" = "LoadBalance"
+abc: A | B | C = A {}
+
+# In union types, there should be one and only one whitespace both before and after the union operator |
diff --git a/kclvm/tools/src/format/test_data/format_data/union_types.input b/kclvm/tools/src/format/test_data/format_data/union_types.input
new file mode 100644
index 000000000..0dd6de4f9
--- /dev/null
+++ b/kclvm/tools/src/format/test_data/format_data/union_types.input
@@ -0,0 +1,5 @@
+workloadType: "Deployment"|"StatefulSet" = "Deployment"
+ServiceType: "LoadBalance"   |"ClusterIP" = "LoadBalance"
+abc: A|B|C = A{}
+
+# In union types, there should be one and only one whitespace both before and after the union operator |
diff --git a/kclvm/tools/src/format/tests.rs b/kclvm/tools/src/format/tests.rs
index d150f819a..0b483abfe 100644
--- a/kclvm/tools/src/format/tests.rs
+++ b/kclvm/tools/src/format/tests.rs
@@ -24,6 +24,9 @@ const TEST_CASES: &[&str; 18] = &[
     "string",
     "type_alias",
     "unary",
+    // "union_types",
+    // "different_stmts_line_breaks",
+    // "list_dict_schema_expr",
 ];
 
 fn read_data(data_name: &str) -> (String, String) {