fix(lib): ForExpression missing iteratorContext and OperatorExpression drops falsy right operands

[X-Guardian]

Related issue

Fixes #111

Description

Bug 1: ForExpression.resolve() does not set iteratorContext

DynamicListTerraformIterator._getForEachExpression() returns a Lazy that checks context.iteratorContext — returning the raw list for "FOR_EXPRESSION" and the map conversion for the default case. TerraformDynamicExpression.resolve() correctly sets context.iteratorContext = "FOR_EXPRESSION" before resolving, but ForExpression.resolve() does not.

Fix: Add context.iteratorContext = "FOR_EXPRESSION" in ForExpression.resolve():

Bug 2: OperatorExpression.resolve() uses truthiness check instead of undefined check

Line 325 uses this.right ? ... : undefined which treats all falsy values (0, false, "") as missing. The - operator branch (line 337) has the same bug.

Fix:

- const right = this.right ? this.resolveArg(context, this.right) : undefined;
+ const right = this.right !== undefined ? this.resolveArg(context, this.right) : undefined;

  case "-": {
-   if (right) {
+   if (right !== undefined) {
      // subtraction
      expr = `(${left} - ${right})`;
    } else {

Checklist

• I have updated the PR title to match CDKTN's style guide
• I have run the linter on my code locally
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation if applicable
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works if applicable
• New and existing unit tests pass locally with my changes

[jsteinich]

I don't believe this is the correct solution. It does work for your example and test case, but I believe it will fail if the input expression actually references a map.

I wonder if DynamicListTerraformIterator should resolve the for each expression with a value set at creation time rather than relying on the current context. Or perhaps the ForExpression needs more information at creation time about the input expression.