core/src/test/java/org/apache/metamodel/intercept/InterceptableDataContextTest.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
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 */
package org.apache.metamodel.intercept;

import java.util.Arrays;
import java.util.List;

import org.apache.metamodel.DataContext;
import org.apache.metamodel.MetaModelHelper;
import org.apache.metamodel.MockUpdateableDataContext;
import org.apache.metamodel.data.DataSet;
import org.apache.metamodel.data.MaxRowsDataSet;
import org.apache.metamodel.query.Query;
import org.apache.metamodel.schema.MutableSchema;
import org.apache.metamodel.schema.Schema;
import org.apache.metamodel.schema.Table;

import junit.framework.TestCase;

public class InterceptableDataContextTest extends TestCase {

    private final MockUpdateableDataContext delegateDataContext = new MockUpdateableDataContext();
    private final Table table = delegateDataContext.getDefaultSchema().getTables().get(0);

    public void testInterceptSchema() throws Exception {
        // without an interceptor
        {
            DataContext dc = new InterceptableDataContext(delegateDataContext);

            Schema schema = dc.getDefaultSchema();
            List<Schema> schemas = dc.getSchemas();

            assertEquals("schema", schema.getName());
            assertEquals(MutableSchema.class, MetaModelHelper.resolveUnderlyingSchema(schema).getClass());
            assertEquals("[information_schema, schema]", Arrays.toString(dc.getSchemaNames().toArray()));
            assertEquals(2, schemas.size());
            assertEquals("information_schema", schemas.get(0).getName());
            assertEquals("schema", schemas.get(1).getName());
        }

        // with an interceptor
        {
            DataContext dc =
                    new InterceptableDataContext(delegateDataContext).addSchemaInterceptor(new SchemaInterceptor() {
                        @Override
                        public Schema intercept(Schema input) {
                            return new MutableSchema(input.getName() + " foo!");
                        }
                    });

            Schema schema = dc.getDefaultSchema();
            List<Schema> schemas = dc.getSchemas();

            assertEquals("schema foo!", schema.getName());
            assertEquals(MutableSchema.class, schema.getClass());
            assertEquals("[information_schema foo!, schema foo!]", Arrays.toString(dc.getSchemaNames().toArray()));
            assertEquals(2, schemas.size());
            assertEquals("information_schema foo!", schemas.get(0).getName());
            assertEquals("schema foo!", schemas.get(1).getName());
        }
    }

    public void testInterceptDataSet() throws Exception {
        DataContext dc =
                new InterceptableDataContext(delegateDataContext).addDataSetInterceptor(new DataSetInterceptor() {
                    @Override
                    public DataSet intercept(DataSet dataSet) {
                        return new MaxRowsDataSet(dataSet, 1);
                    }
                });

        DataSet ds = dc.query().from(table).select("foo").execute();
        assertEquals(MaxRowsDataSet.class, ds.getClass());
        assertEquals(1, ds.toObjectArrays().size());
    }

    public void testInterceptQuery() throws Exception {

        DataContext dc = new InterceptableDataContext(delegateDataContext).addQueryInterceptor(new QueryInterceptor() {
            @Override
            public Query intercept(Query input) {
                return input.select(table.getColumnByName("foo"));
            }
        }).addQueryInterceptor(new QueryInterceptor() {
            @Override
            public Query intercept(Query input) {
                return input.select(table.getColumnByName("bar"));

            }
        });

        DataSet ds = dc.executeQuery(new Query().from(table));
        assertEquals("[table.foo, table.bar]", Arrays.toString(ds.getSelectItems().toArray()));
    }
}