Fix an issue with {% elseif %} expressions inside fragments

[mworrell]

This pull request enhances the template compiler's support for conditional blocks within fragments, specifically adding support for ifequal and ifnotequal constructs and improving how if blocks are handled. It also expands test coverage to ensure correct behavior for these new cases.

Improvements to conditional block handling in fragments:

• Added support for namespacing and processing ifequal and ifnotequal blocks within fragment definitions in the namespace_fragment_element and block_elements functions in template_compiler.erl. This ensures these constructs are correctly recognized and compiled when used inside fragments. [1] [2]

Test coverage enhancements:

• Added new test cases fragment_use_if_test and fragment_use_if_blocks_test to template_compiler_fragment_SUITE.erl to verify correct rendering and block usage for if, ifequal, and ifnotequal within fragments. [1] [2]
• Introduced new template files fragment_if.tpl and fragment_if_blocks.tpl to serve as test data for the new test cases. [1] [2]

[Copilot]

Pull request overview

Enhances the template compiler’s handling of conditional constructs inside fragments, fixing compilation/namespacing for {% if %} blocks with {% elseif %} chains and ensuring block extraction works for ifequal/ifnotequal within fragments. Adds regression tests and fixture templates covering these cases.

Changes:

• Fix fragment block namespacing for if nodes whose Else branch can be an elif-generated nested {'if', ...} AST node.
• Include ifequal/ifnotequal nodes in block traversal so nested blocks inside those conditionals are discovered.
• Add new fragment templates and Common Test cases to validate if/elseif rendering and useblock behavior under if/ifequal/ifnotequal.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/template_compiler.erl	Fixes fragment element namespacing for elseif chains and enables block discovery under ifequal/ifnotequal.
test/template_compiler_fragment_SUITE.erl	Adds tests covering fragment rendering and useblock overrides for the new/adjusted conditional behavior.
test/test-data/fragment_if.tpl	Test fixture for {% if %}...{% elseif %}... inside a fragment.
test/test-data/fragment_if_blocks.tpl	Test fixture for blocks inside if/ifequal/ifnotequal fragments used via useblock.
rebar.lock	Updates cowlib lock version and hashes (appears unrelated to stated PR purpose).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.