Looks like we are not handling the case where an engineer is omitting the {} brackets and using single statements.

if (x == 0) 
  return 1;
else if (x == 1)
  return 2;
else 
  return -1;

We should do that before we enable else if statements

This looks good, let's add a test for

• Where {} are omitted after if statements

I don't love how we pass through isThenBranch and node into this function. Mainly because it's not doing anything with the flags, it simply passes them through to pushStatement. These type of patterns are a code smell that a function is doing a bit too much.

I like that you split this out into its own function and I think doStatement should just eat as many statements as it can and return them in an array.

const doStatement = (ctx: Context) => {
   const statements = [];   
   if (ctx.eat(["{"])) {
      while(...) {
         statements.push(statement(ctx));
      }
      ...
   } else {
      statements = statement(ctx);
     ...
   }

   // filter out null statments, these should really be fixed in general :/
   return statements.filter(stmt => stmt != null);
}

If you apply my comments above we could just do

node.then = doStatement(ctx);

I don't think we need isThenBranch or pushStatement. Let's just simplify a bit by

if (ctx.eat(['if'])) {
   doIfExpression(node, ctx);
   node.then = [...node.then, doStatement(ctx)];
} else {
   node.else = [ ...node.else, doStatement(ctx)];
}

Agreed, i had an uglier implementation before that worked. Your ideea is better. I'll update the PR with the changes (test cases for all branches as well)

Heads up, I added eslint validation to travis so single line if statements will be a warning from now on. Just try to avoid these.

https://travis-ci.org/ballercat/walt/builds/317486874#L485

Thank you for the tests.

Please make test take an i32 argument for x so that we could test all the branches, I want to make sure we cover all the scenarios.

something like this would work

WebAssembly.instantiate(compile(src)).then(({ instance: { exports } }) => {
   t.is(exports.test(0), 2);
   t.is(exports.test(1), 4);
   t.is(exports.test(-1), 1);
});