Add e2e test

This reverts commit 5f2af9050a.

src/query/frontend/ast/ast.lcp

@@ -398,7 +398,7 @@ cpp<#
                ,@(loop for op in
                        '(or-operator xor-operator and-operator addition-operator
                          subtraction-operator multiplication-operator division-operator
-                         mod-operator not-equal-operator equal-operator less-operator
+                         mod-operator not-equal-operator less-operator
                          greater-operator less-equal-operator greater-equal-operator
                          in-list-operator subscript-operator)
                        collecting
@@ -458,6 +458,33 @@ cpp<#
                           (:clone))))))
   (define-unary-operators))
 
+(lcp:define-class equal-operator (binary-operator)
+  ((isNullCheckRequired "bool" :initval "false" :scope :public))
+  (:public
+    #>cpp
+    DEFVISITABLE(ExpressionVisitor<TypedValue>);
+    DEFVISITABLE(ExpressionVisitor<void>);
+
+    bool Accept(HierarchicalTreeVisitor &visitor) override {
+      if (visitor.PreVisit(*this)) {
+        expression1_->Accept(visitor) && expression2_->Accept(visitor);
+      }
+      return visitor.PostVisit(*this);
+    }
+    cpp<#)
+  (:protected
+    #>cpp
+    using BinaryOperator::BinaryOperator;
+    EqualOperator(Expression *expression1, Expression *expression2, bool is_nullcheck_required = false)
+        : BinaryOperator(expression1, expression2), isnullcheckrequired_(is_nullcheck_required) {}
+    cpp<#)
+  (:private
+    #>cpp
+    friend class AstStorage;
+    cpp<#)
+  (:serialize (:slk))
+  (:clone))
+
 (lcp:define-class aggregation (binary-operator)
   ((op "Op" :scope :public)
    (symbol-pos :int32_t :initval -1 :scope :public

src/query/frontend/ast/cypher_main_visitor.cpp

@@ -2267,9 +2267,9 @@ antlrcpp::Any CypherMainVisitor::visitCaseExpression(MemgraphCypher::CaseExpress
   Expression *else_expression = ctx->else_expression ? ctx->else_expression->accept(this).as<Expression *>()
                                                      : storage_->Create<PrimitiveLiteral>(TypedValue());
   for (auto *alternative : alternatives) {
-    Expression *condition =
-        test_expression ? storage_->Create<EqualOperator>(test_expression, alternative->when_expression->accept(this))
-                        : alternative->when_expression->accept(this).as<Expression *>();
+    Expression *condition = test_expression ? storage_->Create<EqualOperator>(
+                                                  test_expression, alternative->when_expression->accept(this), true)
+                                            : alternative->when_expression->accept(this).as<Expression *>();
     Expression *then_expression = alternative->then_expression->accept(this);
     else_expression = storage_->Create<IfOperator>(condition, then_expression, else_expression);
   }

src/query/interpret/eval.hpp

@@ -81,7 +81,6 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
   BINARY_OPERATOR_VISITOR(DivisionOperator, /, /);
   BINARY_OPERATOR_VISITOR(ModOperator, %, %);
   BINARY_OPERATOR_VISITOR(NotEqualOperator, !=, <>);
-  BINARY_OPERATOR_VISITOR(EqualOperator, ==, =);
   BINARY_OPERATOR_VISITOR(LessOperator, <, <);
   BINARY_OPERATOR_VISITOR(GreaterOperator, >, >);
   BINARY_OPERATOR_VISITOR(LessEqualOperator, <=, <=);
@@ -94,6 +93,21 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
 #undef BINARY_OPERATOR_VISITOR
 #undef UNARY_OPERATOR_VISITOR
 
+  TypedValue Visit(EqualOperator &op) override {
+    auto val1 = op.expression1_->Accept(*this);
+    auto val2 = op.expression2_->Accept(*this);
+
+    try {
+      if (op.isnullcheckrequired_ && val2.IsNull()) {
+        throw QueryRuntimeException("Use the generic form when checking against NULL.");
+      }
+
+      return val1 == val2;
+    } catch (const TypedValueException &) {
+      throw QueryRuntimeException("Invalid types: {} and {} for '='.", val1.type(), val2.type());
+    }
+  }
+
   TypedValue Visit(AndOperator &op) override {
     auto value1 = op.expression1_->Accept(*this);
     if (value1.IsBool() && !value1.ValueBool()) {

tests/e2e/CMakeLists.txt

@@ -40,6 +40,7 @@ add_subdirectory(write_procedures)
 add_subdirectory(magic_functions)
 add_subdirectory(module_file_manager)
 add_subdirectory(monitoring_server)
+add_subdirectory(util_e2e)
 
 copy_e2e_python_files(pytest_runner pytest_runner.sh "")
 file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/memgraph-selfsigned.crt DESTINATION ${CMAKE_CURRENT_BINARY_DIR})

tests/e2e/util_e2e/CMakeLists.txt

@@ -0,0 +1,5 @@
+function(copy_util_e2e_python_files FILE_NAME)
+    copy_e2e_python_files(util_e2e ${FILE_NAME})
+endfunction()
+
+copy_util_e2e_python_files(utility_simple.py)

tests/e2e/util_e2e/utility_simple.py

@@ -0,0 +1,40 @@
+# Copyright 2022 Memgraph Ltd.
+#
+# Use of this software is governed by the Business Source License
+# included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+# License, and you may not use this file except in compliance with the Business Source License.
+#
+# As of the Change Date specified in that file, in accordance with
+# the Business Source License, use of this software will be governed
+# by the Apache License, Version 2.0, included in the file
+# licenses/APL.txt.
+
+import typing
+import mgclient
+import sys
+import pytest
+
+
+def test_does_throw_if_null_is_checked_against_in_generic_case():
+
+    connection = mgclient.connect(host="localhost", port=7687)
+    connection.autocommit = True
+
+    cursor = connection.cursor()
+
+    query = """WITH 2 AS name
+                RETURN CASE name
+                WHEN 3 THEN 'works'
+                WHEN null THEN "doesn't work"
+                ELSE 'something went wrong'
+                END"""
+
+    with pytest.raises(mgclient.DatabaseError) as err:
+        cursor.execute(query)
+
+    error_msg = err.value.args[0]
+    assert error_msg == "Use the generic form when checking against NULL."
+
+
+if __name__ == "__main__":
+    sys.exit(pytest.main([__file__, "-rA"]))

tests/e2e/util_e2e/workloads.yaml

@@ -0,0 +1,13 @@
+template_cluster: &template_cluster
+  cluster:
+    main:
+      args: ["--bolt-port", "7687", "--log-level=TRACE"]
+      log_file: "util-e2e.log"
+      setup_queries: []
+      validation_queries: []
+
+workloads:
+  - name: "Utility simple"
+    binary: "tests/e2e/pytest_runner.sh"
+    args: ["util_e2e/utility_simple.py"]
+    <<: *template_cluster

tests/unit/cypher_main_visitor.cpp

@@ -786,6 +786,7 @@ TEST_P(CypherMainVisitorTest, CaseSimpleForm) {
   ASSERT_TRUE(condition);
   ast_generator.CheckLiteral(condition->expression1_, 5);
   ast_generator.CheckLiteral(condition->expression2_, 10);
+  ASSERT_TRUE(condition->isnullcheckrequired_);
   ast_generator.CheckLiteral(if_operator->then_expression_, 1);
   ast_generator.CheckLiteral(if_operator->else_expression_, TypedValue());
 }