Setting metatable manually until setmetatable is available

Using a breakpoint flag on specific opcode to stop the program so we can
manipulate the stack manually within the test

1 files changed, 92 insertions, 5 deletions

diff --git a/tests/ltm.js b/tests/ltm.js
index cb0e38d..5644ae8 100644
--- a/tests/ltm.js
+++ b/tests/ltm.js
@@ -1,12 +1,13 @@
 /*jshint esversion: 6 */
 "use strict";
 
-const test           = require('tape');
-const beautify       = require('js-beautify').js_beautify;
+const test     = require('tape');
+const beautify = require('js-beautify').js_beautify;
 
-const VM             = require("../src/lvm.js");
+const VM       = require("../src/lvm.js");
+const OC       = require('../src/lopcodes.js');
 
-const getState       = require("./tests.js").getState;
+const getState = require("./tests.js").getState;
 
 
 test('__index, __newindex: with actual table', function (t) {
@@ -55,7 +56,6 @@ test('__index: with non table', function (t) {
     t.throws(function () {
         VM.luaV_execute(L);
     }, "Program executed with expected error");
-
 });
 
 
@@ -76,5 +76,92 @@ test('__newindex: with non table', function (t) {
     t.throws(function () {
         VM.luaV_execute(L);
     }, "Program executed with expected error");
+});
+
+
+test('__index function in metatable', function (t) {
+    let luaCode = `
+        local mt = {
+            __index = function (table, key)
+                return "__index"
+            end
+        }
+
+        local t = {}
+
+        -- setmetatable(t, mt)
+
+        return t.yo
+    `, L;
+    
+    t.plan(8);
+
+    t.comment("Running following code: \n" + luaCode);
+
+    t.doesNotThrow(function () {
+        L = getState(luaCode);
+    }, "Bytecode parsed without errors");
+
+
+    // main <hello.lua:0,0> (7 instructions at 0x7fe6b4403050)
+    // 0+ params, 3 slots, 1 upvalue, 2 locals, 2 constants, 1 function
+    //         1       [1]     NEWTABLE        0 0 1
+    //         2       [4]     CLOSURE         1 0     ; 0x7fe6b4403290
+    //         3       [4]     SETTABLE        0 -1 1  ; "__index" -
+    //         4       [7]     NEWTABLE        1 0 0
+    //         5       [9]     GETTABLE        2 1 -2  ; "yo"            <=== We stop here
+    //         6       [9]     RETURN          2 2
+    //         7       [9]     RETURN          0 1
+    //
+    // function <hello.lua:2,4> (3 instructions at 0x7fe6b4403290)
+    // 2 params, 3 slots, 0 upvalues, 2 locals, 1 constant, 0 functions
+    //         1       [3]     LOADK           2 -1    ; "__index"
+    //         2       [3]     RETURN          2 2
+    //         3       [4]     RETURN          0 1
+
+    t.strictEqual(
+        OC.OpCodes[L.stack[0].p.code[4].opcode],
+        "OP_GETTABLE",
+        "Correct opcode marked as breakpoint"
+    );
+
+    t.comment("We set a breakpoint just before 'return t.yo'")
+    L.stack[0].p.code[4].breakpoint = true; // Stop just before 'return t.yo'
+
+    t.doesNotThrow(function () {
+        VM.luaV_execute(L);
+    }, "First part of the program executed without errors");
+
+    t.strictEqual(
+        OC.OpCodes[L.ci.u.l.savedpc[L.ci.pcOff - 1].opcode],
+        "OP_GETTABLE",
+        "Stopped at correct opcode"
+    );
+
+    t.comment("We unset the breakpoint and correct pcOff");
+    L.ci.pcOff--;
+    L.stack[0].p.code[4].breakpoint = false;
+
+    t.ok(
+        L.stack[2].ttistable() && !L.stack[2].value.hash.get("__index"),
+        "t is on stack at 2"
+    );
 
+    t.ok(
+        L.stack[1].ttistable() && L.stack[1].value.hash.get("__index"),
+        "mt is on stack at 1"
+    );
+
+    t.comment("We manually set t's metatable to mt");
+    L.stack[2].metatable = L.stack[1];
+
+    t.doesNotThrow(function () {
+        VM.luaV_execute(L);
+    }, "Second part of the program executed without errors");
+
+    t.strictEqual(
+        L.stack[L.top - 1].value,
+        "__index",
+        "Program output is correct"
+    );
 });
\ No newline at end of file