Add parsing tests that inspect the whole AST

Author: alex-spies

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/expression/Expressions.java

@@ -105,7 +105,9 @@ public static AttributeSet references(List<? extends Expression> exps) {
     }
 
     public static String name(Expression e) {
-        return e instanceof NamedExpression ne ? ne.name() : e.sourceText();
+        return e instanceof Attribute attr && attr.qualifier() != null ? attr.qualifiedName()
+            : e instanceof NamedExpression ne ? ne.name()
+            : e.sourceText();
     }
 
     /**

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/expression/UnresolvedAttribute.java

@@ -68,7 +68,9 @@ public UnresolvedAttribute(
     ) {
         super(source, qualifier, name, id);
         this.customMessage = unresolvedMessage != null;
-        this.unresolvedMsg = unresolvedMessage == null ? errorMessage(name(), null) : unresolvedMessage;
+        this.unresolvedMsg = unresolvedMessage == null
+            ? errorMessage(qualifier() != null ? qualifiedName() : name(), null)
+            : unresolvedMessage;
         this.resolutionMetadata = resolutionMetadata;
     }
 

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/parser/ExpressionBuilder.java

@@ -941,7 +941,7 @@ private Alias visitRerankField(EsqlBaseParser.RerankFieldContext ctx, Source sou
 
         var boolExprCtx = ctx.booleanExpression();
         Expression value = boolExprCtx == null ? id : expression(boolExprCtx);
-        return new Alias(source, id.name(), value);
+        return new Alias(source, source(ctx.qualifiedName()).text(), value);
     }
 
     @Override

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/parser/LogicalPlanBuilder.java

@@ -257,7 +257,7 @@ public PlanFactory visitDissectCommand(EsqlBaseParser.DissectCommandContext ctx)
     public PlanFactory visitMvExpandCommand(EsqlBaseParser.MvExpandCommandContext ctx) {
         UnresolvedAttribute field = visitQualifiedName(ctx.qualifiedName());
         Source src = source(ctx);
-        return child -> new MvExpand(src, child, field, new UnresolvedAttribute(src, field.name()));
+        return child -> new MvExpand(src, child, field, new UnresolvedAttribute(src, field.qualifier(), field.name(), null));
 
     }
 

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/analysis/VerifierTests.java

@@ -388,6 +388,14 @@ public void testAggsExpressionsInStatsAggs() {
             "1:19: grouping key [e] already specified in the STATS BY clause",
             error("from test | stats e BY e = languages + emp_no")
         );
+        assertEquals(
+            "1:19: grouping key [[q].[e]] already specified in the STATS BY clause",
+            error("from test | stats [q].[e] BY [q].[e]")
+        );
+        assertEquals(
+            "1:19: Cannot specify grouping expression [[q].[e]] as an aggregate",
+            error("from test | stats [q].[e] BY x = [q].[e]")
+        );
 
         var message = error("from test | stats languages + emp_no BY e = languages + emp_no");
         assertThat(