Support nested and chained ternaries in recipe parameter resolver

[willdavsmith]

Description

Fixes the direct-module recipe parameter resolver (pkg/recipes/paramresolver/resolver.go) so that chained and nested ternary expressions resolve correctly.

Problem

The resolver evaluated only a single flat == ternary with string-literal arms using one regex. A chained enum mapping like:

size == "S" ? "Basic" : size == "M" ? "Standard" : "Premium"

mis-bound the regex capture groups, so the literal {{...}} expression was passed through verbatim to the IaC engine (Bicep/Terraform) instead of being resolved to the intended value.

Approach (smallest-diff slice)

Only the ternary evaluator is made recursive — nothing else changes:

• Replace the single-level ternaryPattern regex with a condition-only conditionPattern (<context path> == "value").
• Rewrite evaluateTernary as a thin wrapper over a recursive core: evalTernaryExpr, evalTernaryArm, and splitTopLevelTernary.
• splitTopLevelTernary locates the outermost ?/: while skipping quoted string literals and tracking nested ternary depth, so chained/nested arms split and resolve at the correct level.

The public ResolveParameterExpressions signature is unchanged, and the call sites in pkg/recipes/driver/bicep/bicep.go and pkg/recipes/terraform/execute.go are untouched.

Limitations kept by design

These remain as documented limitations (tracked separately on the issue):

• The only supported operator is ==.
• Arms must be string literals or nested ternaries (no context paths or typed results in arms).
• Expressions whose chosen branch cannot be resolved still pass through verbatim rather than failing.

Test coverage

Test_TernaryExpressions now covers 11 cases (5 new), including chained first/middle/default-branch matches, a nested ternary in the true arm, unresolvable-chosen-branch passthrough, and a clarified brace-wrapped passthrough case. All 11 subtests pass; paramresolver, driver/bicep, and driver/terraform packages all pass; go build ./..., go vet, and gofmt are clean.

Addresses #12238

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None

[radius-functional-tests]

Radius functional test overview

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Name	Value
Repository	radius-project/radius
Commit ref	ce2fd90
Unique ID	funcab760c1f7b
Image tag	pr-funcab760c1f7b

• KinD: v0.29.0
• Dapr: 1.14.4
• Azure KeyVault CSI driver: 1.4.2
• Azure Workload identity webhook: 1.3.0
• Bicep recipe location ghcr.io/radius-project/dev/test/testrecipes/test-bicep-recipes/<name>:pr-funcab760c1f7b
• Terraform recipe location http://tf-module-server.radius-test-tf-module-server.svc.cluster.local/<name>.zip (in cluster)
• applications-rp test image location: ghcr.io/radius-project/dev/applications-rp:pr-funcab760c1f7b
• dynamic-rp test image location: ghcr.io/radius-project/dev/dynamic-rp:pr-funcab760c1f7b
• controller test image location: ghcr.io/radius-project/dev/controller:pr-funcab760c1f7b
• ucp test image location: ghcr.io/radius-project/dev/ucpd:pr-funcab760c1f7b
• deployment-engine test image location: ghcr.io/radius-project/deployment-engine:latest

Test Status

⌛ Building Radius and pushing container images for functional tests...
✅ Container images build succeeded
⌛ Publishing Bicep Recipes for functional tests...
✅ Recipe publishing succeeded
⌛ Starting ucp-cloud functional tests...
⌛ Starting corerp-cloud functional tests...
✅ ucp-cloud functional tests succeeded
✅ corerp-cloud functional tests succeeded

[Copilot]

Pull request overview

This PR updates the direct-module recipe parameter resolver’s ternary evaluation logic so chained and nested ternary expressions inside {{ ... }} are parsed and resolved correctly, addressing the regex mis-binding issue described in #12238.

Changes:

• Replaces the single-level ternary regex with a condition-only regex and introduces a recursive ternary evaluator.
• Adds a scanner (splitTopLevelTernary) to split at the outermost ? / matching : while skipping quoted strings and tracking nesting depth.
• Expands unit tests to cover chained and nested ternary scenarios, plus passthrough cases.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
pkg/recipes/paramresolver/resolver.go	Reworks ternary parsing/evaluation to support chained/nested ternaries via recursion and a top-level split scanner.
pkg/recipes/paramresolver/resolver_test.go	Adds/updates ternary-focused test cases covering chained/nested resolution and passthrough behavior.

[github-actions]

Unit Tests

    2 files  ±0    442 suites  ±0   7m 23s ⏱️ -10s
5 547 tests +5  5 545 ✅ +5  2 💤 ±0  0 ❌ ±0 
6 727 runs  +5  6 725 ✅ +5  2 💤 ±0  0 ❌ ±0 

Results for commit ce2fd90. ± Comparison against base commit 547cf38.

This pull request removes 1 and adds 6 tests. Note that renamed tests count towards both.

github.com/radius-project/radius/pkg/recipes/paramresolver ‑ Test_TernaryExpressions/nested/chained_ternary_left_as-is_(out_of_scope)

github.com/radius-project/radius/pkg/recipes/paramresolver ‑ Test_TernaryExpressions/brace-wrapped_nested_ternary_left_as-is_(outer_scanner_stops_at_first_brace)
github.com/radius-project/radius/pkg/recipes/paramresolver ‑ Test_TernaryExpressions/chained_ternary_-_default_branch_matches
github.com/radius-project/radius/pkg/recipes/paramresolver ‑ Test_TernaryExpressions/chained_ternary_-_first_branch_matches
github.com/radius-project/radius/pkg/recipes/paramresolver ‑ Test_TernaryExpressions/chained_ternary_-_middle_branch_matches
github.com/radius-project/radius/pkg/recipes/paramresolver ‑ Test_TernaryExpressions/chained_ternary_with_unresolvable_condition_on_chosen_branch_left_as-is
github.com/radius-project/radius/pkg/recipes/paramresolver ‑ Test_TernaryExpressions/nested_ternary_in_true_arm

[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 52.83%. Comparing base (547cf38) to head (ce2fd90).

Files with missing lines	Patch %	Lines
pkg/recipes/paramresolver/resolver.go	90.00%	3 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12239      +/-   ##
==========================================
+ Coverage   52.82%   52.83%   +0.01%     
==========================================
  Files         743      743              
  Lines       47788    47828      +40     
==========================================
+ Hits        25242    25269      +27     
- Misses      20195    20202       +7     
- Partials     2351     2357       +6     

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