Support BigQuery ASSERT statement

Adds ASSERT expression [AS description] as a statement, wired through
the statement visitors, deparser and table-name finder. ASSERT stays a
non-reserved keyword.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EqinwHBKuAtPEmtXr3b5P2

Author: hayssams

src/main/java/net/sf/jsqlparser/statement/AssertStatement.java

@@ -0,0 +1,81 @@
+/*-
+ * #%L
+ * JSQLParser library
+ * %%
+ * Copyright (C) 2004 - 2026 JSQLParser
+ * %%
+ * Dual licensed under GNU LGPL 2.1 or Apache License 2.0
+ * #L%
+ */
+package net.sf.jsqlparser.statement;
+
+import net.sf.jsqlparser.expression.Expression;
+import net.sf.jsqlparser.expression.StringValue;
+
+/**
+ * BigQuery's {@code ASSERT expression [AS description]}, which fails the script when the expression
+ * does not evaluate to {@code TRUE}.
+ *
+ * @see <a href=
+ *      "https://cloud.google.com/bigquery/docs/reference/standard-sql/debugging-statements">Debugging
+ *      statements</a>
+ */
+public class AssertStatement implements Statement {
+    private Expression expression;
+    private StringValue description;
+
+    public AssertStatement() {}
+
+    public AssertStatement(Expression expression) {
+        this.expression = expression;
+    }
+
+    public AssertStatement(Expression expression, StringValue description) {
+        this.expression = expression;
+        this.description = description;
+    }
+
+    public Expression getExpression() {
+        return expression;
+    }
+
+    public void setExpression(Expression expression) {
+        this.expression = expression;
+    }
+
+    public AssertStatement withExpression(Expression expression) {
+        setExpression(expression);
+        return this;
+    }
+
+    public StringValue getDescription() {
+        return description;
+    }
+
+    public void setDescription(StringValue description) {
+        this.description = description;
+    }
+
+    public AssertStatement withDescription(StringValue description) {
+        setDescription(description);
+        return this;
+    }
+
+    public StringBuilder appendTo(StringBuilder builder) {
+        builder.append("ASSERT ").append(expression);
+        if (description != null) {
+            builder.append(" AS ").append(description);
+        }
+        return builder;
+    }
+
+    @Override
+    public String toString() {
+        return appendTo(new StringBuilder()).toString();
+    }
+
+    @Override
+    public <T, S> T accept(StatementVisitor<T> statementVisitor, S context) {
+        return statementVisitor.visit(this, context);
+    }
+}

src/main/java/net/sf/jsqlparser/statement/StatementFeatureVisitor.java

@@ -521,6 +521,13 @@ public <S> Void visit(Drop drop, S context) {
         return null;
     }
 
+    @Override
+    public <S> Void visit(AssertStatement assertStatement, S context) {
+        analysis.claimTopLevel();
+        analysis.certain(StmtFeature.READS_DATA);
+        return null;
+    }
+
     @Override
     public <S> Void visit(PurgeStatement purgeStatement, S context) {
         analysis.claimTopLevel();

src/main/java/net/sf/jsqlparser/statement/StatementVisitor.java

@@ -371,6 +371,12 @@ default void visit(RenameTableStatement renameTableStatement) {
         this.visit(renameTableStatement, null);
     }
 
+    <S> T visit(AssertStatement assertStatement, S context);
+
+    default void visit(AssertStatement assertStatement) {
+        this.visit(assertStatement, null);
+    }
+
     <S> T visit(PurgeStatement purgeStatement, S context);
 
     default void visit(PurgeStatement purgeStatement) {

src/main/java/net/sf/jsqlparser/statement/StatementVisitorAdapter.java

@@ -618,6 +618,11 @@ public <S> T visit(RenameTableStatement renameTableStatement, S context) {
         return null;
     }
 
+    @Override
+    public <S> T visit(AssertStatement assertStatement, S context) {
+        return null;
+    }
+
     @Override
     public <S> T visit(PurgeStatement purgeStatement, S context) {
         return null;

src/main/java/net/sf/jsqlparser/util/TablesNamesFinder.java

@@ -209,6 +209,7 @@
 import net.sf.jsqlparser.statement.update.Update;
 import net.sf.jsqlparser.statement.update.UpdateSet;
 import net.sf.jsqlparser.statement.upsert.Upsert;
+import net.sf.jsqlparser.statement.AssertStatement;
 
 
 /**
@@ -2464,6 +2465,17 @@ public void visit(RenameTableStatement renameTableStatement) {
         StatementVisitor.super.visit(renameTableStatement);
     }
 
+    @Override
+    public <S> Void visit(AssertStatement assertStatement, S context) {
+        assertStatement.getExpression().accept(this, context);
+        return null;
+    }
+
+    @Override
+    public void visit(AssertStatement assertStatement) {
+        StatementVisitor.super.visit(assertStatement);
+    }
+
     @Override
     public <S> Void visit(PurgeStatement purgeStatement, S context) {
         if (purgeStatement.getPurgeObjectType() == PurgeObjectType.TABLE) {

src/main/java/net/sf/jsqlparser/util/deparser/StatementDeParser.java

@@ -97,6 +97,7 @@
 import net.sf.jsqlparser.statement.update.ParenthesedUpdate;
 import net.sf.jsqlparser.statement.update.Update;
 import net.sf.jsqlparser.statement.upsert.Upsert;
+import net.sf.jsqlparser.statement.AssertStatement;
 
 public class StatementDeParser extends AbstractDeParser<Statement>
         implements StatementVisitor<StringBuilder> {
@@ -552,6 +553,12 @@ public <S> StringBuilder visit(RenameTableStatement renameTableStatement, S cont
         return builder;
     }
 
+    @Override
+    public <S> StringBuilder visit(AssertStatement assertStatement, S context) {
+        assertStatement.appendTo(builder);
+        return builder;
+    }
+
     @Override
     public <S> StringBuilder visit(PurgeStatement purgeStatement, S context) {
         purgeStatement.appendTo(builder);

src/main/java/net/sf/jsqlparser/util/validation/validator/StatementValidator.java

@@ -99,6 +99,7 @@
 import net.sf.jsqlparser.statement.upsert.Upsert;
 import net.sf.jsqlparser.util.validation.ValidationCapability;
 import net.sf.jsqlparser.util.validation.metadata.NamedObject;
+import net.sf.jsqlparser.statement.AssertStatement;
 
 /**
  * @author gitmotte
@@ -477,6 +478,12 @@ public <S> Void visit(RenameTableStatement renameTableStatement, S context) {
         return null;
     }
 
+    @Override
+    public <S> Void visit(AssertStatement assertStatement, S context) {
+        // TODO: not yet implemented
+        return null;
+    }
+
     @Override
     public <S> Void visit(PurgeStatement purgeStatement, S context) {
         // TODO: not yet implemented
@@ -693,6 +700,10 @@ public void visit(RenameTableStatement renameTableStatement) {
         visit(renameTableStatement, null);
     }
 
+    public void visit(AssertStatement assertStatement) {
+        visit(assertStatement, null);
+    }
+
     public void visit(PurgeStatement purgeStatement) {
         visit(purgeStatement, null);
     }

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -1933,6 +1933,7 @@ String NonReservedWord() :
       | tk=<K_APPLY:"APPLY">
       | tk=<K_APPROXIMATE:"APPROXIMATE">
       | tk=<K_ARCHIVE: "ARCHIVE">
+      | tk=<K_ASSERT: "ASSERT">
       | tk=<K_ARRAY_LITERAL: "ARRAY" >
       | tk=<K_ASYMMETRIC: "ASYMMETRIC">
       | tk=<K_AT: "AT">
@@ -2912,6 +2913,8 @@ Statement SingleStatement() :
             |
             LOOKAHEAD({ isKeywordAhead("REVOKE") }) stm = Revoke(false)
             |
+            LOOKAHEAD({ getToken(1).kind == K_ASSERT }) stm = AssertStatement()
+            |
             stm = PurgeStatement()
             |
             stm = SessionStatement()
@@ -4313,6 +4316,22 @@ RenameTableStatement RenameTableStatement(): {
     }
 }
 
+/**
+ * BigQuery's ASSERT expression [AS description] debugging statement.
+ */
+AssertStatement AssertStatement() #AssertStatement:
+{
+    AssertStatement assertStatement = new AssertStatement();
+    Expression expression;
+    Token token;
+}
+{
+    <K_ASSERT> expression=Expression() { assertStatement.setExpression(expression); }
+    [ <K_AS> token=<S_CHAR_LITERAL>
+        { assertStatement.setDescription(new StringValue(token.image)); } ]
+    { return assertStatement; }
+}
+
 PurgeStatement PurgeStatement(): {
     PurgeStatement purgeStatement = null;
     Table table;

src/test/java/net/sf/jsqlparser/statement/select/BigQueryTest.java

@@ -11,6 +11,7 @@
 
 import net.sf.jsqlparser.JSQLParserException;
 import net.sf.jsqlparser.expression.ArrayExpression;
+import net.sf.jsqlparser.statement.AssertStatement;
 import net.sf.jsqlparser.statement.create.table.CreateTable;
 import net.sf.jsqlparser.statement.create.table.TablePartitioning;
 import net.sf.jsqlparser.test.TestUtils;
@@ -214,4 +215,28 @@ void testCreateTablePartitionByHashStillParses() throws JSQLParserException {
         Assertions.assertEquals(TablePartitioning.Type.HASH,
                 createTable.getPartitioning().getType());
     }
+
+    @Test
+    void testAssertStatementWithDescription() throws JSQLParserException {
+        String sqlStr = "ASSERT (SELECT COUNT(*) FROM t) > 0 AS 'table is empty'";
+        AssertStatement assertStatement =
+                (AssertStatement) TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr, true);
+
+        Assertions.assertEquals("'table is empty'", assertStatement.getDescription().toString());
+    }
+
+    @Test
+    void testAssertStatementWithoutDescription() throws JSQLParserException {
+        String sqlStr = "ASSERT EXISTS(SELECT 1 FROM t)";
+        AssertStatement assertStatement =
+                (AssertStatement) TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr, true);
+
+        Assertions.assertNull(assertStatement.getDescription());
+    }
+
+    @Test
+    void testAssertRemainsUsableAsIdentifier() throws JSQLParserException {
+        String sqlStr = "SELECT assert FROM t";
+        TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr, true);
+    }
 }