[Varshith-Kali]

Fixes #4873

Problem

A literal Fn::FindInMap whose map name or keys are not in Mappings was reported only where the surrounding schema constrains the value. In a Condition operand, an Fn::Join item, an Fn::Sub variable, or an unconstrained property, no rule reported it, even though CloudFormation rejects the template at ValidateTemplate with Template error: Unable to get mapping for ....

The cause is the early return in BaseFn.resolve when the target schema carries no constraining keyword: the map and key check runs only during that resolution.

Fix

Override resolve in FindInMap so resolution still runs for its errors when there are no schema constraints, while value validation still only runs when constraints exist. The per-position rule attribution is unchanged, so the issue's templates now report exactly as 1.46.0 did: E8003 in a Condition operand, E1022 in an Fn::Join item, E1019 in an Fn::Sub variable, and E1011 in a constrained property.

Deliberately not changed:

• Lookups with a DefaultValue still do not report a bad key, since the lookup cannot fail at deploy time.
• Keys resolved from a parameter Default still do not report, since a deployer can override them (same rule as the constrained path).
• Unconstrained positions gain no new resolved-value findings, only definite lookup failures.

Verification

Reproduced all four issue positions on current main first (no output, exit code 0, except the control). After the fix, each reports its rule at the lookup, and the constrained control still reports E1011 with no duplicates.

Test results (run against the branch source):

• test/unit/rules/functions/test_find_in_map.py: 23 passed (6 new unconstrained-path cases)
• test/unit/rules/functions/ and test/unit/rules/conditions/: 338 passed
• test/unit/rules/: 2086 passed
• test/unit/module/: 1022 passed, 9 failed. The 9 failures are pre-existing on unmodified main (CLI arg listing, pricing specs, graph tests) and are unrelated to this change.
• ruff check and ruff format --check clean on all touched files.

[Varshith-Kali]

Hi maintainers, the CI workflow run for this PR is waiting on first-time-contributor approval. Could someone approve the run when you get a chance? Thanks!

[OKAN-SOFTWARE]

Validated commit a6bc768 locally using Python 3.12.14.

• All 338 function and condition tests passed, including the 23 FindInMap tests.
• Nine full-template checks through cfnlint.api.lint passed.
• Replacing the implementation with current main produced 3 failures and 20 passes in the focused suite, confirming the new error-detection coverage.

Confirmed that missing lookup keys are reported in condition operands, Fn::Join items, Fn::Sub variables, and Lambda environment variables. The constrained-property control still reports exactly one error.

Valid lookups and DefaultValue fallbacks—including a missing map with a fallback—remain accepted. Failures originating from an overridable parameter Default remain suppressed.

No blocking issue found within the reviewed scope. Validation was local; no AWS deployment was performed.

[Varshith-Kali]

Thanks for validating this locally, including the focused-suite comparison against main and the constrained-property control. No action on my side from this review; the PR still awaits maintainer review and the first-time-contributor CI approval.

[Varshith-Kali]

Rebased onto current main: the branch had gone dirty after #4810 merged. The only conflict was in test_find_in_map.py, where #4810 added the map-name-from-parameter-Default cases to the same test region. Resolution keeps both sets intact: #4810's cases stay with test_resolve_map_name_from_parameter_default, and this PR's cases stay with test_resolve_without_schema_constraints. Verified locally: 30/30 in test_find_in_map.py and 306 passed across test/unit/rules/functions/, ruff clean.

[OKAN-SOFTWARE]

Thanks for rebasing and preserving both regression test groups.
The updated diff looks consistent with my earlier review. No further concerns from my side.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.75%. Comparing base (4c7581a) to head (b43b7a0).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4919   +/-   ##
=======================================
  Coverage   94.75%   94.75%           
=======================================
  Files         442      442           
  Lines       16105    16120   +15     
  Branches     3125     3130    +5     
=======================================
+ Hits        15260    15275   +15     
  Misses        466      466           
  Partials      379      379           

Flag	Coverage Δ
unittests	94.75% <100.00%> (+<0.01%)	⬆️

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