[TS]: builder, Fix requiredField(). Verity that the field is present in the vtable (#7739) (#7752)

* [TS]: Fix vtable creation for consecutive required fileds (#7739)

* handle feedback

* comment the schema

* comment change in builder.ts

* [TS]: builder, Fix requiredField()

Verifty that the field is present in the vtable.

* restore monsterdata binary file

Co-authored-by: Derek Bailey <derekbailey@google.com>

8 files changed, 163 insertions, 2 deletions

diff --git a/tests/required_strings.fbs b/tests/required_strings.fbs
new file mode 100644
index 00000000..98556d4f
--- /dev/null
+++ b/tests/required_strings.fbs
@@ -0,0 +1,12 @@
+namespace required_strings;
+
+/**
+ * Foo defines a type where both fields are mandatory.
+ * The creation of a Foo buffer must throw if either of the fields is missing.
+ *
+ * https://github.com/google/flatbuffers/issues/7739
+ */
+table Foo {
+  str_a:string (required);
+  str_b:string (required);
+}
diff --git a/tests/ts/JavaScriptRequiredStringTest.js b/tests/ts/JavaScriptRequiredStringTest.js
new file mode 100644
index 00000000..6023ef80
--- /dev/null
+++ b/tests/ts/JavaScriptRequiredStringTest.js
@@ -0,0 +1,32 @@
+import assert from 'assert'
+import * as flatbuffers from 'flatbuffers';
+import { Foo } from './required-strings/foo.js';
+
+
+var builder = new flatbuffers.Builder();
+
+function main() {
+  testMissingFirstRequiredString();
+  builder.clear();
+  testMissingSecondRequiredString();
+}
+
+function testMissingFirstRequiredString() {
+	const undefined_string = builder.createString(undefined);
+	const defined_string = builder.createString('cat');
+
+	assert.throws(() => Foo.createFoo(
+		builder, undefined_string, defined_string
+	));
+}
+
+function testMissingSecondRequiredString() {
+	const defined_string = builder.createString('cat');
+	const undefined_string = builder.createString(undefined);
+
+	assert.throws(() => Foo.createFoo(
+		builder, defined_string, undefined_string
+	));
+}
+
+main();
diff --git a/tests/ts/TypeScriptTest.py b/tests/ts/TypeScriptTest.py
index 4fe7ab65..4a4ccb2a 100755
--- a/tests/ts/TypeScriptTest.py
+++ b/tests/ts/TypeScriptTest.py
@@ -134,4 +134,5 @@ print("Running TypeScript Tests...")
 check_call(NODE_CMD + ["JavaScriptTest"])
 check_call(NODE_CMD + ["JavaScriptUnionVectorTest"])
 check_call(NODE_CMD + ["JavaScriptFlexBuffersTest"])
-check_call(NODE_CMD + ["JavaScriptComplexArraysTest"])
\ No newline at end of file
+check_call(NODE_CMD + ["JavaScriptComplexArraysTest"])
+check_call(NODE_CMD + ["JavaScriptRequiredStringTest"])
diff --git a/tests/ts/required-strings/foo.js b/tests/ts/required-strings/foo.js
new file mode 100644
index 00000000..774fcca1
--- /dev/null
+++ b/tests/ts/required-strings/foo.js
@@ -0,0 +1,49 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+import * as flatbuffers from 'flatbuffers';
+export class Foo {
+    constructor() {
+        this.bb = null;
+        this.bb_pos = 0;
+    }
+    __init(i, bb) {
+        this.bb_pos = i;
+        this.bb = bb;
+        return this;
+    }
+    static getRootAsFoo(bb, obj) {
+        return (obj || new Foo()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+    }
+    static getSizePrefixedRootAsFoo(bb, obj) {
+        bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+        return (obj || new Foo()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+    }
+    strA(optionalEncoding) {
+        const offset = this.bb.__offset(this.bb_pos, 4);
+        return offset ? this.bb.__string(this.bb_pos + offset, optionalEncoding) : null;
+    }
+    strB(optionalEncoding) {
+        const offset = this.bb.__offset(this.bb_pos, 6);
+        return offset ? this.bb.__string(this.bb_pos + offset, optionalEncoding) : null;
+    }
+    static startFoo(builder) {
+        builder.startObject(2);
+    }
+    static addStrA(builder, strAOffset) {
+        builder.addFieldOffset(0, strAOffset, 0);
+    }
+    static addStrB(builder, strBOffset) {
+        builder.addFieldOffset(1, strBOffset, 0);
+    }
+    static endFoo(builder) {
+        const offset = builder.endObject();
+        builder.requiredField(offset, 4); // str_a
+        builder.requiredField(offset, 6); // str_b
+        return offset;
+    }
+    static createFoo(builder, strAOffset, strBOffset) {
+        Foo.startFoo(builder);
+        Foo.addStrA(builder, strAOffset);
+        Foo.addStrB(builder, strBOffset);
+        return Foo.endFoo(builder);
+    }
+}
diff --git a/tests/ts/required-strings/foo.ts b/tests/ts/required-strings/foo.ts
new file mode 100644
index 00000000..8ae6666c
--- /dev/null
+++ b/tests/ts/required-strings/foo.ts
@@ -0,0 +1,62 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+import * as flatbuffers from 'flatbuffers';
+
+export class Foo {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):Foo {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsFoo(bb:flatbuffers.ByteBuffer, obj?:Foo):Foo {
+  return (obj || new Foo()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsFoo(bb:flatbuffers.ByteBuffer, obj?:Foo):Foo {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new Foo()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+strA():string|null
+strA(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+strA(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+strB():string|null
+strB(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+strB(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 6);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+static startFoo(builder:flatbuffers.Builder) {
+  builder.startObject(2);
+}
+
+static addStrA(builder:flatbuffers.Builder, strAOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(0, strAOffset, 0);
+}
+
+static addStrB(builder:flatbuffers.Builder, strBOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(1, strBOffset, 0);
+}
+
+static endFoo(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  builder.requiredField(offset, 4) // str_a
+  builder.requiredField(offset, 6) // str_b
+  return offset;
+}
+
+static createFoo(builder:flatbuffers.Builder, strAOffset:flatbuffers.Offset, strBOffset:flatbuffers.Offset):flatbuffers.Offset {
+  Foo.startFoo(builder);
+  Foo.addStrA(builder, strAOffset);
+  Foo.addStrB(builder, strBOffset);
+  return Foo.endFoo(builder);
+}
+}
diff --git a/tests/ts/required_strings_generated.js b/tests/ts/required_strings_generated.js
new file mode 100644
index 00000000..9f9cf017
--- /dev/null
+++ b/tests/ts/required_strings_generated.js
@@ -0,0 +1,2 @@
+"use strict";
+// automatically generated by the FlatBuffers compiler, do not modify
diff --git a/tests/ts/required_strings_generated.ts b/tests/ts/required_strings_generated.ts
new file mode 100644
index 00000000..b7d545f8
--- /dev/null
+++ b/tests/ts/required_strings_generated.ts
@@ -0,0 +1,2 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
diff --git a/ts/builder.ts b/ts/builder.ts
index f1a2b419..4ba34035 100644
--- a/ts/builder.ts
+++ b/ts/builder.ts
@@ -458,7 +458,8 @@ export class Builder {
     requiredField(table: Offset, field: number): void {
       const table_start = this.bb.capacity() - table;
       const vtable_start = table_start - this.bb.readInt32(table_start);
-      const ok = this.bb.readInt16(vtable_start + field) != 0;
+      const ok = field < this.bb.readInt16(vtable_start) &&
+                 this.bb.readInt16(vtable_start + field) != 0;
   
       // If this fails, the caller will show what field needs to be set.
       if (!ok) {