feat: Support union underlying type for TS/JS (#7961)

tests/parser_test.cpp

@@ -845,7 +845,7 @@ void ParseUnionTest() {
   // Test union underlying type
   const char *source = "table A {} table B {} union U : int {A, B} table C {test_union: U; test_vector_of_union: [U];}";
   flatbuffers::Parser parser3;
-  parser3.opts.lang_to_generate = flatbuffers::IDLOptions::kCpp;
+  parser3.opts.lang_to_generate = flatbuffers::IDLOptions::kCpp | flatbuffers::IDLOptions::kTs;
   TEST_EQ(parser3.Parse(source), true);
   
   parser3.opts.lang_to_generate &= flatbuffers::IDLOptions::kJava;

tests/ts/JavaScriptUnionUnderlyingTypeTest.js

@@ -0,0 +1,26 @@
+import assert from 'assert'
+import * as flatbuffers from 'flatbuffers'
+import {UnionUnderlyingType as Test} from './union_underlying_type_test.js'
+
+function main() {
+    let a = new Test.AT();
+    a.a = 1;
+    let b = new Test.BT();
+    b.b = "foo";
+    let c = new Test.CT();
+    c.c = true;
+    let d = new Test.DT();
+    d.testUnionType = Test.ABC.A;
+    d.testUnion = a;
+    d.testVectorOfUnionType = [Test.ABC.A, Test.ABC.B, Test.ABC.C];
+    d.testVectorOfUnion = [a, b, c];
+
+    let fbb = new flatbuffers.Builder();
+    let offset = d.pack(fbb);
+    fbb.finish(offset);
+
+    let unpacked = Test.D.getRootAsD(fbb.dataBuffer()).unpack();
+    assert.equal(JSON.stringify(unpacked), JSON.stringify(d));
+}
+
+main()

tests/ts/TypeScriptTest.py

@@ -117,6 +117,11 @@ flatc(
 )
 esbuild("typescript_keywords.ts", "typescript_keywords_generated.cjs")
 
+flatc(
+    options=["--ts", "--reflect-names", "--gen-name-strings", "--gen-mutable", "--gen-object-api", "--ts-entry-points", "--ts-flat-files"],
+    schema="../union_underlying_type_test.fbs"
+)
+
 print("Running TypeScript Compiler...")
 check_call(["tsc"])
 print("Running TypeScript Compiler in old node resolution mode for no_import_ext...")
@@ -129,6 +134,7 @@ check_call(NODE_CMD + ["JavaScriptTest"])
 check_call(NODE_CMD + ["JavaScriptUnionVectorTest"])
 check_call(NODE_CMD + ["JavaScriptFlexBuffersTest"])
 check_call(NODE_CMD + ["JavaScriptComplexArraysTest"])
+check_call(NODE_CMD + ["JavaScriptUnionUnderlyingTypeTest"])
 
 print("Running old v1 TypeScript Tests...")
 check_call(NODE_CMD + ["JavaScriptTestv1.cjs", "./monster_test_generated.cjs"])

tests/ts/tsconfig.json

@@ -14,6 +14,7 @@
     "optional_scalars/**/*.ts",
     "namespace_test/**/*.ts",
     "union_vector/**/*.ts",
-    "arrays_test_complex/**/*.ts"
+    "arrays_test_complex/**/*.ts",
+    "union_underlying_type_test.ts"
   ]
 }