AVRO-3786: [Rust] Deserialization results in FindUnionVariant error i…

…f the writer and reader have the same symbol but at different positions (#2335)

Add the test case from the JIRA ticket.
Update the assertions to actually match the expected behavior.

Signed-off-by: Martin Tzvetanov Grigorov <mgrigorov@apache.org>

lang/rust/avro/tests/avro-3786.rs

@@ -0,0 +1,159 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use apache_avro::{from_avro_datum, to_avro_datum, to_value, types, Schema};
+use apache_avro_test_helper::TestResult;
+
+#[test]
+fn avro_3786_deserialize_union_with_different_enum_order() -> TestResult {
+    #[derive(Debug, PartialEq, Eq, Clone, serde::Deserialize, serde::Serialize)]
+    pub struct BarUseParent {
+        #[serde(rename = "barUse")]
+        pub bar_use: Bar,
+    }
+
+    #[derive(
+        Debug, PartialEq, Eq, Hash, PartialOrd, Ord, Clone, serde::Deserialize, serde::Serialize,
+    )]
+    pub enum Bar {
+        #[serde(rename = "bar0")]
+        Bar0,
+        #[serde(rename = "bar1")]
+        Bar1,
+        #[serde(rename = "bar2")]
+        Bar2,
+    }
+
+    #[derive(Debug, PartialEq, Eq, Clone, serde::Deserialize, serde::Serialize)]
+    pub struct Foo {
+        #[serde(rename = "barInit")]
+        pub bar_init: Bar,
+        #[serde(rename = "barUseParent")]
+        pub bar_use_parent: Option<BarUseParent>,
+    }
+
+    let writer_schema = r#"{
+            "type": "record",
+            "name": "Foo",
+            "fields":
+            [
+                {
+                    "name": "barInit",
+                    "type":
+                    {
+                        "type": "enum",
+                        "name": "Bar",
+                        "symbols":
+                        [
+                            "bar0",
+                            "bar1",
+                            "bar2"
+                        ],
+                        "default": "bar0"
+                    }
+                },
+                {
+                    "name": "barUseParent",
+                    "type": [
+                        "null",
+                        {
+                            "type": "record",
+                            "name": "BarUseParent",
+                            "fields": [
+                                {
+                                    "name": "barUse",
+                                    "type": "Bar"
+                                }
+                            ]
+                        }
+                    ]
+                }
+            ]
+        }"#;
+
+    let reader_schema = r#"{
+            "type": "record",
+            "name": "Foo",
+            "fields":
+            [
+                {
+                    "name": "barInit",
+                    "type":
+                    {
+                        "type": "enum",
+                        "name": "Bar",
+                        "symbols":
+                        [
+                            "bar1"
+                        ],
+                        "default": "bar1"
+                    }
+                },
+                {
+                    "name": "barUseParent",
+                    "type": [
+                        "null",
+                        {
+                            "type": "record",
+                            "name": "BarUseParent",
+                            "fields": [
+                                {
+                                    "name": "barUse",
+                                    "type": "Bar"
+                                }
+                            ]
+                        }
+                    ]
+                }
+            ]
+            }"#;
+
+    let writer_schema = Schema::parse_str(writer_schema)?;
+    let foo1 = Foo {
+        bar_init: Bar::Bar1,
+        bar_use_parent: Some(BarUseParent { bar_use: Bar::Bar1 }),
+    };
+    let avro_value = crate::to_value(foo1)?;
+    assert!(
+        avro_value.validate(&writer_schema),
+        "value is valid for schema",
+    );
+    let datum = crate::to_avro_datum(&writer_schema, avro_value)?;
+    let mut x = &datum[..];
+    let reader_schema = Schema::parse_str(reader_schema)?;
+    let deser_value = crate::from_avro_datum(&writer_schema, &mut x, Some(&reader_schema))?;
+    match deser_value {
+        types::Value::Record(fields) => {
+            assert_eq!(fields.len(), 2);
+            assert_eq!(fields[0].0, "barInit");
+            assert_eq!(fields[0].1, types::Value::Enum(0, "bar1".to_string()));
+            assert_eq!(fields[1].0, "barUseParent");
+            assert_eq!(
+                fields[1].1,
+                types::Value::Union(
+                    1,
+                    Box::new(types::Value::Record(vec![(
+                        "barUse".to_string(),
+                        types::Value::Enum(0, "bar1".to_string())
+                    )]))
+                )
+            );
+        }
+        _ => panic!("Expected Value::Record"),
+    }
+    Ok(())
+}