text: ////////////////////////////////////////////////////////////////////////////////
  /// DISCLAIMER
  ///
  /// Copyright 2014-2020 ArangoDB GmbH, Cologne, Germany
  /// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
  ///
  /// Licensed under the Apache License, Version 2.0 (the "License");
  /// you may not use this file except in compliance with the License.
  /// You may obtain a copy of the License at
  ///
  ///     http://www.apache.org/licenses/LICENSE-2.0
  ///
  /// Unless required by applicable law or agreed to in writing, software
  /// distributed under the License is distributed on an "AS IS" BASIS,
  /// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  /// See the License for the specific language governing permissions and
  /// limitations under the License.
  ///
  /// Copyright holder is ArangoDB GmbH, Cologne, Germany
  ///
  /// @author Markus Pfeiffer
  ////////////////////////////////////////////////////////////////////////////////
  
  #include "Mocks/Servers.h"
  #include "QueryHelper.h"
  #include "gtest/gtest.h"
  
  #include "Aql/Query.h"
  #include "RestServer/QueryRegistryFeature.h"
  
  #include <velocypack/Buffer.h>
  #include <velocypack/Builder.h>
  #include <velocypack/Iterator.h>
  #include <velocypack/Slice.h>
  #include <velocypack/velocypack-aliases.h>
  
  #include "../IResearch/IResearchQueryCommon.h"
  
  #include "Logger/LogMacros.h"
  
  using namespace arangodb;
  using namespace arangodb::aql;
  
  namespace arangodb {
  namespace tests {
  namespace aql {
  
  class RemoveExecutorTest : public ::testing::Test {
   protected:
    mocks::MockAqlServer server;
    TRI_vocbase_t& vocbase;
  
    std::string const collectionName = "UnitTestCollection";
    std::string const allDocumentsQuery =
        std::string("FOR d IN " + collectionName + " RETURN d");
  
   public:
    RemoveExecutorTest() : vocbase(server.getSystemDatabase()) {}
  
    void SetUp() override {
      SCOPED_TRACE("SetUp");
      auto info = VPackParser::fromJson("{\"name\": \"" + collectionName + "\"}");
      auto collection = vocbase.createCollection(info->slice());
      ASSERT_NE(collection.get(), nullptr) << "Failed to create collection";
  
      std::string createQuery =
          "FOR i IN 1..1000 INSERT { _key: TO_STRING(i), value: i, sortvalue: i "
          "} IN " +
          collectionName;
      AssertQueryHasResult(vocbase, createQuery, VPackSlice::emptyArraySlice());
    }
  };
  
  class RemoveExecutorTestPatterns
      : public RemoveExecutorTest,
        public ::testing::WithParamInterface<std::pair<size_t, size_t>> {
   public:
    size_t const nDocs;
    std::string const nDocsString;
    size_t const rDocs;
    std::string const rDocsString;
  
    RemoveExecutorTestPatterns()
        : nDocs(GetParam().first),
          nDocsString(std::to_string(GetParam().first)),
          rDocs(GetParam().second),
          rDocsString(std::to_string(GetParam().second)) {}
  
    void SetUp() override {
      SCOPED_TRACE("SetUp");
      auto info = VPackParser::fromJson("{\"name\": \"" + collectionName + "\"}");
      auto collection = vocbase.createCollection(info->slice());
      ASSERT_NE(collection.get(), nullptr) << "Failed to create collection";
  
      std::string createQuery = "FOR i IN 1.." + nDocsString +
                                " INSERT { _key: TO_STRING(i), "
                                "value: i, sortvalue: i "
                                "} IN " +
                                collectionName;
      AssertQueryHasResult(vocbase, createQuery, VPackSlice::emptyArraySlice());
    }
  };
  
  TEST_F(RemoveExecutorTest, remove_non_existent_assert_error) {
    std::string query =
        std::string("REMOVE { _key: \"invalidFoo\"} IN " + collectionName);
  
    AssertQueryFailsWith(vocbase, query, TRI_ERROR_ARANGO_DOCUMENT_NOT_FOUND);
  }
  
  TEST_F(RemoveExecutorTest, remove_non_existent_ignore_error) {
    auto const expected = VPackParser::fromJson("[ ]");
    std::string query =
        std::string("REMOVE { _key: \"invalidFoo\"} IN " + collectionName +
                    " OPTIONS { ignoreErrors: true }");
  
    AssertQueryHasResult(vocbase, query, expected->slice());
  }
  
  TEST_P(RemoveExecutorTestPatterns, remove_all_without_return) {
    std::string query = std::string("FOR d IN " + collectionName +
                                    " REMOVE d IN " + collectionName);
  
    AssertQueryHasResult(vocbase, query, VPackSlice::emptyArraySlice());
  
    AssertQueryHasResult(vocbase, allDocumentsQuery,
                         VPackSlice::emptyArraySlice());
  }
  
  TEST_P(RemoveExecutorTestPatterns, remove_all_with_return) {
    auto const bindParameters = VPackParser::fromJson("{ }");
    std::string allQuery =
        std::string("FOR d IN " + collectionName + " RETURN d");
  
    auto allDocs = executeQuery(vocbase, allQuery, bindParameters);
    ASSERT_TRUE(allDocs.ok());
  
    std::string query =
        std::string("FOR d IN " + collectionName + " REMOVE d IN " +
                    collectionName + " RETURN OLD");
    AssertQueryHasResult(vocbase, query, allDocs.data->slice());
  
    AssertQueryHasResult(vocbase, allDocumentsQuery,
                         VPackSlice::emptyArraySlice());
  }
  
  TEST_P(RemoveExecutorTestPatterns, remove_every_third_without_return) {
    std::string query =
        std::string("FOR d IN " + collectionName +
                    " FILTER (d.value % 3) == 0 REMOVE d IN " + collectionName);
  
    AssertQueryHasResult(vocbase, query, VPackSlice::emptyArraySlice());
  
    std::string checkQuery =
        "FOR d IN " + collectionName + " FILTER d.value % 3 == 0 RETURN d.value";
    AssertQueryHasResult(vocbase, checkQuery, VPackSlice::emptyArraySlice());
  
    // The things we did not remove still have to be there.
    {
      std::string checkQuery =
          "FOR d IN " + collectionName +
          " FILTER (d.value % 3) != 0 SORT d.value RETURN d.value";
      VPackBuilder builder;
      builder.openArray();
      for (size_t i = 1; i <= nDocs; i++) {
        if (i % 3 != 0) {
          builder.add(VPackValue(i));
        }
      }
      builder.close();
      AssertQueryHasResult(vocbase, checkQuery, builder.slice());
    }
  }
  
  TEST_P(RemoveExecutorTestPatterns, remove_every_third_with_return) {
    auto const bindParameters = VPackParser::fromJson("{ }");
    std::string allQuery =
        std::string("FOR d IN " + collectionName +
                    " FILTER (d.value % 3) == 0 SORT d.value RETURN d");
  
    auto allDocs = executeQuery(vocbase, allQuery, bindParameters);
    ASSERT_TRUE(allDocs.ok());
  
    std::string query = std::string(
        "FOR d IN " + collectionName + " FILTER (d.value % 3) == 0 REMOVE d IN " +
        collectionName + " SORT OLD.value RETURN OLD");
    AssertQueryHasResult(vocbase, query, allDocs.data->slice());
  
    // The things we did not remove still have to be there.
    {
      std::string checkQuery =
          "FOR d IN " + collectionName +
          " FILTER (d.value % 3) != 0 SORT d.value RETURN d.value";
      VPackBuilder builder;
      builder.openArray();
      for (size_t i = 1; i <= nDocs; i++) {
        if (i % 3 != 0) {
          builder.add(VPackValue(i));
        }
      }
      builder.close();
      AssertQueryHasResult(vocbase, checkQuery, builder.slice());
    }
  }
  
  TEST_P(RemoveExecutorTestPatterns, remove_with_key) {
    auto const bindParameters = VPackParser::fromJson("{ }");
    std::string docQuery = std::string("FOR d IN " + collectionName +
                                       " FILTER d.value <= " + rDocsString +
                                       " SORT d.sortvalue RETURN d");
  
    auto docs = executeQuery(vocbase, docQuery, bindParameters);
    ASSERT_TRUE(docs.ok());
  
    std::string query = std::string("FOR i IN 1.." + rDocsString +
                                    " REMOVE { _key: TO_STRING(i) } IN " +
                                    collectionName + " RETURN OLD");
    AssertQueryHasResult(vocbase, query, docs.data->slice());
  }
  
  TEST_P(RemoveExecutorTestPatterns, remove_with_id) {
    auto const bindParameters = VPackParser::fromJson("{ }");
    std::string allQuery =
        std::string("FOR d IN " + collectionName + " RETURN d");
  
    auto allDocs = executeQuery(vocbase, allQuery, bindParameters);
    ASSERT_TRUE(allDocs.ok());
  
    std::string query = R"aql(FOR d IN )aql" + collectionName +
                        R"aql( REMOVE { _key: d._key } IN )aql" + collectionName +
                        R"aql( RETURN OLD)aql";
  
    AssertQueryHasResult(vocbase, query, allDocs.data->slice());
  }
  
  TEST_P(RemoveExecutorTestPatterns, remove_all_without_return_subquery) {
    auto const expected = VPackParser::fromJson("[[ ]]");
    std::string query =
        std::string("FOR i in 1..1 LET x = (FOR d IN " + collectionName +
                    " REMOVE d IN " + collectionName + ") RETURN x");
  
    AssertQueryHasResult(vocbase, query, expected->slice());
  
    std::string checkQuery = "FOR i IN " + collectionName + " RETURN i.value";
    AssertQueryHasResult(vocbase, checkQuery, VPackSlice::emptyArraySlice());
  }
  
  INSTANTIATE_TEST_CASE_P(
      RemoveExecutorTestInstance, RemoveExecutorTestPatterns,
      testing::Values(std::pair{100, 10}, std::pair{1000, 10},
                      std::pair{1000, 100}, std::pair{999, 10},
                      std::pair{1001, 1000}, std::pair{1001, 1001},
                      std::pair{2001, 1000}, std::pair{2001, 1500},
                      std::pair{3000, 1000}, std::pair{3000, 2001}));
  
  }  // namespace aql
  }  // namespace tests
  }  // namespace arangodb
  