test that verifies the default value bug

Author: ruolin59

coral-schema/src/test/java/com/linkedin/coral/schema/avro/SchemaUtilitiesTests.java

@@ -90,4 +90,22 @@ public void testToNullableSchema() {
 
     Assert.assertEquals(outputSchema.toString(true), TestUtils.loadSchema("testToNullableSchema-expected.avsc"));
   }
+
+  /**
+   * Test that ToLowercaseSchemaVisitor properly lowercases field names in default values.
+   * This test demonstrates the bug where complex default values (records, maps, arrays)
+   * retain their original casing while the schema itself is lowercased.
+   */
+  @Test
+  public void testLowercaseSchemaWithComplexDefaultValues() {
+    Schema inputSchema =
+        AvroCompatibilityHelper.parse(TestUtils.loadSchema("testLowercaseSchemaWithDefaultValues-input.avsc"));
+    Schema outputSchema = ToLowercaseSchemaVisitor.visit(inputSchema);
+
+    // Compare with expected output, trimming whitespace for comparison
+    String expected = TestUtils.loadSchema("testLowercaseSchemaWithDefaultValues-expected.avsc").trim();
+    String actual = outputSchema.toString(true).trim();
+    
+    Assert.assertEquals(actual, expected);
+  }
 }

coral-schema/src/test/resources/testLowercaseSchemaWithDefaultValues-expected.avsc

@@ -0,0 +1,60 @@
+{
+  "type" : "record",
+  "name" : "testrecord",
+  "namespace" : "com.test",
+  "fields" : [ {
+    "name" : "simple_field",
+    "type" : "int",
+    "default" : 42
+  }, {
+    "name" : "struct_field",
+    "type" : {
+      "type" : "record",
+      "name" : "nestedrecord",
+      "fields" : [ {
+        "name" : "firstname",
+        "type" : "string"
+      }, {
+        "name" : "lastname",
+        "type" : "string"
+      }, {
+        "name" : "age",
+        "type" : "int"
+      } ]
+    },
+    "default" : {
+      "firstname" : "John",
+      "lastname" : "Doe",
+      "age" : 30
+    }
+  }, {
+    "name" : "map_field",
+    "type" : {
+      "type" : "map",
+      "values" : "string"
+    },
+    "default" : {
+      "key_one" : "value1",
+      "key_two" : "value2"
+    }
+  }, {
+    "name" : "array_field",
+    "type" : {
+      "type" : "array",
+      "items" : {
+        "type" : "record",
+        "name" : "arrayitem",
+        "fields" : [ {
+          "name" : "item_name",
+          "type" : "string"
+        } ]
+      }
+    },
+    "default" : [ {
+      "item_name" : "item1"
+    }, {
+      "item_name" : "item2"
+    } ]
+  } ]
+}
+

coral-schema/src/test/resources/testLowercaseSchemaWithDefaultValues-input.avsc

@@ -0,0 +1,60 @@
+{
+  "type" : "record",
+  "name" : "TestRecord",
+  "namespace" : "com.test",
+  "fields" : [ {
+    "name" : "Simple_Field",
+    "type" : "int",
+    "default" : 42
+  }, {
+    "name" : "Struct_Field",
+    "type" : {
+      "type" : "record",
+      "name" : "NestedRecord",
+      "fields" : [ {
+        "name" : "firstName",
+        "type" : "string"
+      }, {
+        "name" : "lastName",
+        "type" : "string"
+      }, {
+        "name" : "Age",
+        "type" : "int"
+      } ]
+    },
+    "default" : {
+      "firstName" : "John",
+      "lastName" : "Doe",
+      "Age" : 30
+    }
+  }, {
+    "name" : "Map_Field",
+    "type" : {
+      "type" : "map",
+      "values" : "string"
+    },
+    "default" : {
+      "Key_One" : "value1",
+      "Key_Two" : "value2"
+    }
+  }, {
+    "name" : "Array_Field",
+    "type" : {
+      "type" : "array",
+      "items" : {
+        "type" : "record",
+        "name" : "ArrayItem",
+        "fields" : [ {
+          "name" : "Item_Name",
+          "type" : "string"
+        } ]
+      }
+    },
+    "default" : [ {
+      "Item_Name" : "item1"
+    }, {
+      "Item_Name" : "item2"
+    } ]
+  } ]
+}
+