[rust] fix: make enumUnknownDefaultCase catch unknown enum values

modules/openapi-generator/src/main/resources/rust/model.mustache

@@ -25,6 +25,11 @@ use serde_repr::{Serialize_repr,Deserialize_repr};
 pub enum {{{classname}}} {
 {{#allowableValues}}
 {{#enumVars}}
+{{#-last}}
+{{#enumUnknownDefaultCase}}
+    #[serde(other)]
+{{/enumUnknownDefaultCase}}
+{{/-last}}
     {{{name}}} = {{{value}}},
 {{/enumVars}}{{/allowableValues}}
 }
@@ -51,6 +56,11 @@ pub enum {{{classname}}} {
 {{#allowableValues}}
 {{#enumVars}}
     #[serde(rename = "{{{value}}}")]
+{{#-last}}
+{{#enumUnknownDefaultCase}}
+    #[serde(other)]
+{{/enumUnknownDefaultCase}}
+{{/-last}}
     {{{name}}},
 {{/enumVars}}{{/allowableValues}}
 }
@@ -216,6 +226,11 @@ impl Default for {{classname}} {
 pub enum {{{enumName}}} {
 {{#allowableValues}}
 {{#enumVars}}
+{{#-last}}
+{{#enumUnknownDefaultCase}}
+    #[serde(other)]
+{{/enumUnknownDefaultCase}}
+{{/-last}}
     {{{name}}} = {{{value}}},
 {{/enumVars}}
 {{/allowableValues}}
@@ -240,6 +255,11 @@ pub enum {{{enumName}}} {
 {{#allowableValues}}
 {{#enumVars}}
     #[serde(rename = "{{{value}}}")]
+{{#-last}}
+{{#enumUnknownDefaultCase}}
+    #[serde(other)]
+{{/enumUnknownDefaultCase}}
+{{/-last}}
     {{{name}}},
 {{/enumVars}}
 {{/allowableValues}}

modules/openapi-generator/src/test/java/org/openapitools/codegen/rust/RustClientCodegenTest.java

@@ -550,4 +550,31 @@ public void testReqwestPathParameterSpaceEncoding() throws IOException {
             TestUtils.assertFileContains(Path.of(target.toString(), "/Cargo.toml"), "percent-encoding");
         }
     }
-}
+
+    @Test
+    public void testEnumUnknownDefaultCaseUsesSerdeOther() throws IOException {
+        Path target = Files.createTempDirectory("test");
+        target.toFile().deleteOnExit();
+        final CodegenConfigurator configurator = new CodegenConfigurator()
+                .setGeneratorName("rust")
+                .addAdditionalProperty(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, true)
+                .setInputSpec("src/test/resources/3_0/rust/enum-unknown-default-case.yaml")
+                .setSkipOverwrite(false)
+                .setOutputDir(target.toAbsolutePath().toString().replace("\\", "/"));
+        List<File> files = new DefaultGenerator().opts(configurator.toClientOptInput()).generate();
+        files.forEach(File::deleteOnExit);
+
+        // string enum schema
+        Path petKindPath = Path.of(target.toString(), "/src/models/pet_kind.rs");
+        TestUtils.assertFileExists(petKindPath);
+        TestUtils.assertFileContains(petKindPath,
+                "#[serde(rename = \"unknown_default_open_api\")] #[serde(other)] UnknownDefaultOpenApi,");
+
+        // inline string and integer property enums
+        Path petPath = Path.of(target.toString(), "/src/models/pet.rs");
+        TestUtils.assertFileExists(petPath);
+        TestUtils.assertFileContains(petPath,
+                "#[serde(rename = \"unknown_default_open_api\")] #[serde(other)] UnknownDefaultOpenApi,",
+                "#[serde(other)] UnknownDefaultOpenApi = 11184809,");
+    }
+}

modules/openapi-generator/src/test/resources/3_0/rust/enum-unknown-default-case.yaml

@@ -0,0 +1,41 @@
+openapi: 3.0.3
+info:
+  title: Enum unknown default case
+  version: 1.0.0
+paths:
+  /pets:
+    get:
+      operationId: listPets
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/Pet'
+components:
+  schemas:
+    Pet:
+      type: object
+      required:
+        - kind
+      properties:
+        kind:
+          $ref: '#/components/schemas/PetKind'
+        status:
+          type: string
+          enum:
+            - available
+            - sold
+        size:
+          type: integer
+          enum:
+            - 1
+            - 2
+    PetKind:
+      type: string
+      enum:
+        - cat
+        - dog