fix(validation): validate inline expressions via the condition AST instead of reporting them as one missing variable

[vaceslav]

Problem

ValidateTemplate (Word TemplateValidator/ScopedVariableValidator, OpenDocument OdtTemplateValidator, and the TemplateProcessor facade) treated an inline expression placeholder such as {{(A and B)}}, {{(IsActive):yesno}} or {{(Price > 100)}} as a single variable named (A and B):

• with data, it reported Variable '(A and B)' is referenced in the template but not provided in the data. as a MissingVariable error, and listed (A and B) in MissingVariables, even when every operand was present. So IsValid was false for a correct template.
• AllPlaceholders contained the expression text ((A and B)) and not the variables it uses.
• expressions that cannot be parsed ({{(A and)}}, {{(A && B)}}) were not reported. Processing leaves them unreplaced with an ExpressionFailed warning.

Fix

The new Core/InlineExpressionValidation.cs is shared by both validators. It parses inline expressions with the same parser processing uses (ConditionAstCache.InlineExpressions, which also allows single-quoted strings):

• Syntax: an expression that cannot be parsed is an InvalidConditionalExpression error (Invalid expression '(A and)': ..., location = the placeholder). It is reported with or without data, once per message.
• AllPlaceholders: gets the variables the expression references, taken from the AST (as for {{#if}} conditions). Operators, literals and keywords are not listed. An expression that cannot be parsed adds nothing. Word and OpenDocument behave the same.
• Missing variables (with data): a MissingVariable error (Variable 'X' is referenced in expression '(...)' but not provided in the data.) and a MissingVariables entry are reported for each variable that processing reads from the data without a fallback and that cannot be resolved in the loop scope. Item properties, named iteration variables, @ metadata and ./this resolve as in processing. The checked variables are:
  • operands tested for truthiness: the whole expression, and the operands of and/or/not. A missing one evaluates to false.
  • variable operands of in, contains, startswith and endswith. These are resolved strictly, so a missing one is null.
• Not reported (mirrors processing):
  • comparison operands and list items. The inline dialect uses the shared ResolveOrLiteral, so an unresolved bareword is a string literal ({{(Status = Active)}}, {{(Missing > 100)}}).
  • operands of exists, is empty and is not empty.
• MissingConditionVariable warning (feat(validation): warn about missing variables used as bare condition operands #231): not added for inline expressions. Their missing truthiness operands are already MissingVariable errors, so the warning would repeat them.

Tests

• New Integration/ValidationInlineExpressionTests.cs. Every case is validated as Word and as OpenDocument, directly and through the facade, and the results must be identical. Cases:
  • valid expressions (logical, format specifiers, comparisons, nested parentheses, single and double quotes, bareword literals, in/contains/startswith, exists/is empty, literals). For each one the test also processes the template and asserts no missing variables and no warnings, so validation predicts processing.
  • AllPlaceholders content.
  • missing operands (truthiness, nested, dotted, in/string operators, (Missing) = true not reported).
  • no data.
  • unparsable expressions, with and without data. For these the test also processes the template and asserts an ExpressionFailed warning and that the text is left unchanged.
  • duplicates.
  • loops: item properties, named variables, metadata, globals, a missing item property, an item property used outside the loop, an empty loop.
  • conditional branches, table cells and headers.
• OdtValidationParityTests: new "inline expressions" template.
• ValidationMissingConditionVariableTests: the inline test now also asserts the MissingVariable error.
• The Release build in CI mode has 0 warnings. All tests pass on net10/net9/net8 (plus Converter and Tools tests). Validation tests also pass under tr-TR and ar-SA. dotnet format --verify-no-changes, dotnet pack and mkdocs build --strict pass.

Docs: docs/for-developers/quick-start.md, TriasDev.Templify/README.md (ValidationResult), ARCHITECTURE.md.

Public API impact: none (validation results: false errors removed)

This is a bug fix to validation results of the shipped ValidateTemplate API. There are no signature changes.

• False MissingVariable errors and MissingVariables entries for inline expressions whose operands are present are gone.
• Missing operands are now reported by their real names (B instead of (A and B)).
• AllPlaceholders lists an expression's variables instead of the expression text.
• New correct errors: MissingVariable for genuinely missing operands, and InvalidConditionalExpression for expressions that processing cannot evaluate (also without data).

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Codecov Report

❌ Patch coverage is 98.50746% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...iasDev.Templify/Core/InlineExpressionValidation.cs	97.67%	0 Missing and 1 partial ⚠️

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