Translate undefined as nil

Perryvw · Perryvw · commit cbe3d38e36e9 · 2018-05-10T17:58:46.000+02:00
diff --git a/src/Transpiler.ts b/src/Transpiler.ts
@@ -566,7 +566,11 @@ export class LuaTranspiler {
             case ts.SyntaxKind.ElementAccessExpression:
                 return this.transpileElementAccessExpression(node as ts.ElementAccessExpression);
             case ts.SyntaxKind.Identifier:
-                // For identifiers simply return their name
+                // Catch undefined which is passed as identifier
+                if ((node as ts.Identifier).originalKeywordKind === ts.SyntaxKind.UndefinedKeyword) {
+                    return "nil";
+                }
+                // Otherwise simply return the name
                 return (node as ts.Identifier).text;
             case ts.SyntaxKind.StringLiteral:
                 const text = (node as ts.StringLiteral).text;
@@ -580,6 +584,7 @@ export class LuaTranspiler {
             case ts.SyntaxKind.FalseKeyword:
                 return "false";
             case ts.SyntaxKind.NullKeyword:
+            case ts.SyntaxKind.UndefinedKeyword:
                 return "nil";
             case ts.SyntaxKind.ThisKeyword:
                 return "self";
diff --git a/test/unit/assignments.spec.ts b/test/unit/assignments.spec.ts
@@ -13,7 +13,7 @@ export class AssignmentTests {
     @TestCase(`{a:3,b:"4"}`, `{a = 3,b = "4"}`)
     @Test("Const assignment")
     public constAssignment(inp: string, out: string) {
-        var lua = util.transpileString(`const myvar = ${inp};`)
+        const lua = util.transpileString(`const myvar = ${inp};`);
         Expect(lua).toBe(`local myvar = ${out}`);
     }
 
@@ -25,7 +25,7 @@ export class AssignmentTests {
     @TestCase(`{a:3,b:"4"}`, `{a = 3,b = "4"}`)
     @Test("Const assignment")
     public letAssignment(inp: string, out: string) {
-        var lua = util.transpileString(`let myvar = ${inp};`)
+        const lua = util.transpileString(`let myvar = ${inp};`);
         Expect(lua).toBe(`local myvar = ${out}`);
     }
 
@@ -37,7 +37,19 @@ export class AssignmentTests {
     @TestCase(`{a:3,b:"4"}`, `{a = 3,b = "4"}`)
     @Test("Const assignment")
     public varAssignment(inp: string, out: string) {
-        var lua = util.transpileString(`var myvar = ${inp};`)
+        const lua = util.transpileString(`var myvar = ${inp};`);
         Expect(lua).toBe(`local myvar = ${out}`);
     }
+
+    @TestCase("var myvar;")
+    @TestCase("let myvar;")
+    @TestCase("const myvar;")
+    @TestCase("const myvar = null;")
+    @TestCase("const myvar = undefined;")
+    @Test("Null assignments")
+    public nullAssignment(declaration: string) {
+        const lua = util.transpileString(declaration + " return myvar;");
+        const result = util.executeLua(lua);
+        Expect(result).toBe(undefined);
+    }
 }
