fix!: add unique union types for Python (#1982)

docs/migrations/version-3-to-4.md

@@ -95,6 +95,10 @@ Console.WriteLine(dateTime2);
 
 Models are aiming to be >= v3.7 compliant.
 
+### Unique types in unions
+
+In v4, unions types are rendered unique, meaning you will never see `str | str` but just `str`.
+
 ### Pydantic now follows v2 instead of v1
 
 Reference: https://docs.pydantic.dev/2.6/migration/

src/generators/python/PythonConstrainer.ts

@@ -50,7 +50,8 @@ export const PythonDefaultTypeMapping: PythonTypeMapping = {
     const unionTypes = constrainedModel.union.map((unionModel) => {
       return unionModel.type;
     });
-    return unionTypes.join(' | ');
+    const uniqueSet = new Set(unionTypes);
+    return [...uniqueSet].join(' | ');
   },
   Dictionary({ constrainedModel }): string {
     return `dict[${constrainedModel.key.type}, ${constrainedModel.value.type}]`;

test/generators/python/PythonConstrainer.spec.ts

@@ -199,6 +199,29 @@ describe('PythonConstrainer', () => {
       expect(type).toEqual('str');
     });
     test('should render multiple types', () => {
+      const unionModel1 = new ConstrainedStringModel(
+        'test',
+        undefined,
+        {},
+        'str'
+      );
+      const unionModel2 = new ConstrainedStringModel(
+        'test',
+        undefined,
+        {},
+        'str2'
+      );
+      const model = new ConstrainedUnionModel('test', undefined, {}, '', [
+        unionModel1,
+        unionModel2
+      ]);
+      const type = PythonDefaultTypeMapping.Union({
+        constrainedModel: model,
+        ...defaultOptions
+      });
+      expect(type).toEqual('str | str2');
+    });
+    test('should render unique types', () => {
       const unionModel1 = new ConstrainedStringModel(
         'test',
         undefined,
@@ -219,7 +242,7 @@ describe('PythonConstrainer', () => {
         constrainedModel: model,
         ...defaultOptions
       });
-      expect(type).toEqual('str | str');
+      expect(type).toEqual('str');
     });
   });
 

test/runtime/runtime-python.spec.ts

@@ -9,8 +9,8 @@ test("Python runtime testing", async () => {
 
     const compileCommand = `cd ${path.resolve(
         __dirname,
-        "./runtime-python/test/"
-    )} && python3 main.py`;
+        "./runtime-python"
+    )} && python3 -m unittest discover ./tests`;
     await execCommand(compileCommand,true);
 
 });

test/runtime/runtime-python/tests/__init__.py

@@ -0,0 +1,7 @@
+import os
+import sys
+PROJECT_PATH = os.getcwd()
+SOURCE_PATH = os.path.join(
+    PROJECT_PATH, "src"
+)
+sys.path.append(SOURCE_PATH)

test/runtime/runtime-python/test/main.py → test/runtime/runtime-python/tests/main.py

@@ -1,8 +1,6 @@
 import unittest
-import sys
-sys.path.insert(1, '../src/main/')
-from Address import Address
-from NestedObject import NestedObject
+from src.main.Address import Address
+from src.main.NestedObject import NestedObject
 import json
 
 class TestAddress(unittest.TestCase):