Fix VCS text eval tests for out-of-tree builds

VCS functions returned "<unknown>" when no repo was found, but
the tests guarded on IsEmpty(), so assertions ran against the
sentinel string and failed. This happened whenever the build
directory lived outside the source tree.

Move the "<unknown>" fallback from the VCS data layer up to the
parser's presentation layer. The VCS functions now return empty
strings on failure, and the parser applies the display fallback.

Rewrite the test fixture to create a temporary git repo with a
known commit, author, and email. Tests no longer depend on the
ambient git environment and produce deterministic results from
any build directory.

common/text_eval/text_eval_parser.cpp

@@ -677,7 +677,13 @@ auto EVAL_VISITOR::evaluateFunction( const FUNC_DATA& aFunc ) const -> Result<Va
     }
 
     // VCS functions (return strings!)
-    else if( name == "vcsidentifier" && argc <= 1 )
+    // Empty results from the VCS layer mean "not in a repository" or "no data available"
+    auto vcsResult = []( const std::string& aResult ) -> std::string
+    {
+        return aResult.empty() ? "<unknown>" : aResult;
+    };
+
+    if( name == "vcsidentifier" && argc <= 1 )
     {
         int length = 40; // Full identifier by default
 
@@ -689,7 +695,7 @@ auto EVAL_VISITOR::evaluateFunction( const FUNC_DATA& aFunc ) const -> Result<Va
                 length = static_cast<int>( lenResult.GetValue() );
         }
 
-        return MakeValue<Value>( TEXT_EVAL_VCS::GetCommitHash( ".", length ) );
+        return MakeValue<Value>( vcsResult( TEXT_EVAL_VCS::GetCommitHash( ".", length ) ) );
     }
     else if( name == "vcsnearestlabel" && argc <= 2 )
     {
@@ -707,7 +713,7 @@ auto EVAL_VISITOR::evaluateFunction( const FUNC_DATA& aFunc ) const -> Result<Va
                 anyTags = tagsResult.GetValue() != 0.0;
         }
 
-        return MakeValue<Value>( TEXT_EVAL_VCS::GetNearestTag( match, anyTags ) );
+        return MakeValue<Value>( vcsResult( TEXT_EVAL_VCS::GetNearestTag( match, anyTags ) ) );
     }
     else if( name == "vcslabeldistance" && argc <= 2 )
     {
@@ -761,23 +767,23 @@ auto EVAL_VISITOR::evaluateFunction( const FUNC_DATA& aFunc ) const -> Result<Va
     }
     else if( name == "vcsauthor" && argc == 0 )
     {
-        return MakeValue<Value>( TEXT_EVAL_VCS::GetAuthor( "." ) );
+        return MakeValue<Value>( vcsResult( TEXT_EVAL_VCS::GetAuthor( "." ) ) );
     }
     else if( name == "vcsauthoremail" && argc == 0 )
     {
-        return MakeValue<Value>( TEXT_EVAL_VCS::GetAuthorEmail( "." ) );
+        return MakeValue<Value>( vcsResult( TEXT_EVAL_VCS::GetAuthorEmail( "." ) ) );
     }
     else if( name == "vcscommitter" && argc == 0 )
     {
-        return MakeValue<Value>( TEXT_EVAL_VCS::GetCommitter( "." ) );
+        return MakeValue<Value>( vcsResult( TEXT_EVAL_VCS::GetCommitter( "." ) ) );
     }
     else if( name == "vcscommitteremail" && argc == 0 )
     {
-        return MakeValue<Value>( TEXT_EVAL_VCS::GetCommitterEmail( "." ) );
+        return MakeValue<Value>( vcsResult( TEXT_EVAL_VCS::GetCommitterEmail( "." ) ) );
     }
     else if( name == "vcsbranch" && argc == 0 )
     {
-        return MakeValue<Value>( TEXT_EVAL_VCS::GetBranch() );
+        return MakeValue<Value>( vcsResult( TEXT_EVAL_VCS::GetBranch() ) );
     }
     else if( name == "vcscommitdate" && argc <= 1 )
     {
@@ -789,7 +795,7 @@ auto EVAL_VISITOR::evaluateFunction( const FUNC_DATA& aFunc ) const -> Result<Va
         int64_t timestamp = TEXT_EVAL_VCS::GetCommitTimestamp( "." );
 
         if( timestamp == 0 )
-            return MakeValue<Value>( "" );
+            return MakeValue<Value>( vcsResult( std::string() ) );
 
         int days = static_cast<int>( timestamp / ( 24 * 3600 ) );
         return MakeValue<Value>( DATE_UTILS::FormatDate( days, format ) );
@@ -809,27 +815,27 @@ auto EVAL_VISITOR::evaluateFunction( const FUNC_DATA& aFunc ) const -> Result<Va
                 length = static_cast<int>( lenResult.GetValue() );
         }
 
-        return MakeValue<Value>( TEXT_EVAL_VCS::GetCommitHash( filePath, length ) );
+        return MakeValue<Value>( vcsResult( TEXT_EVAL_VCS::GetCommitHash( filePath, length ) ) );
     }
     else if( name == "vcsfileauthor" && argc == 1 )
     {
         std::string filePath = VALUE_UTILS::ToString( argValues[0] );
-        return MakeValue<Value>( TEXT_EVAL_VCS::GetAuthor( filePath ) );
+        return MakeValue<Value>( vcsResult( TEXT_EVAL_VCS::GetAuthor( filePath ) ) );
     }
     else if( name == "vcsfileauthoremail" && argc == 1 )
     {
         std::string filePath = VALUE_UTILS::ToString( argValues[0] );
-        return MakeValue<Value>( TEXT_EVAL_VCS::GetAuthorEmail( filePath ) );
+        return MakeValue<Value>( vcsResult( TEXT_EVAL_VCS::GetAuthorEmail( filePath ) ) );
     }
     else if( name == "vcsfilecommitter" && argc == 1 )
     {
         std::string filePath = VALUE_UTILS::ToString( argValues[0] );
-        return MakeValue<Value>( TEXT_EVAL_VCS::GetCommitter( filePath ) );
+        return MakeValue<Value>( vcsResult( TEXT_EVAL_VCS::GetCommitter( filePath ) ) );
     }
     else if( name == "vcsfilecommitteremail" && argc == 1 )
     {
         std::string filePath = VALUE_UTILS::ToString( argValues[0] );
-        return MakeValue<Value>( TEXT_EVAL_VCS::GetCommitterEmail( filePath ) );
+        return MakeValue<Value>( vcsResult( TEXT_EVAL_VCS::GetCommitterEmail( filePath ) ) );
     }
     else if( name == "vcsfilecommitdate" && argc >= 1 && argc <= 2 )
     {
@@ -842,7 +848,7 @@ auto EVAL_VISITOR::evaluateFunction( const FUNC_DATA& aFunc ) const -> Result<Va
         int64_t timestamp = TEXT_EVAL_VCS::GetCommitTimestamp( filePath );
 
         if( timestamp == 0 )
-            return MakeValue<Value>( "" );
+            return MakeValue<Value>( vcsResult( std::string() ) );
 
         int days = static_cast<int>( timestamp / ( 24 * 3600 ) );
         return MakeValue<Value>( DATE_UTILS::FormatDate( days, format ) );