commons-rdf-simple/src/test/java/org/apache/commons/rdf/simple/experimental/AbstractRDFParserTest.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 under the License.
 */
package org.apache.commons.rdf.simple.experimental;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;
import static org.junit.Assume.assumeNotNull;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.concurrent.TimeUnit;

import org.apache.commons.rdf.api.Graph;
import org.apache.commons.rdf.api.IRI;
import org.apache.commons.rdf.api.Literal;
import org.apache.commons.rdf.api.RDFSyntax;
import org.apache.commons.rdf.api.RDFTerm;
import org.apache.commons.rdf.api.RDF;
import org.apache.commons.rdf.api.Triple;
import org.apache.commons.rdf.experimental.RDFParser;
import org.apache.commons.rdf.simple.DummyRDFParserBuilder;
import org.apache.commons.rdf.simple.SimpleRDF;
import org.apache.commons.rdf.simple.Types;
import org.junit.After;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;

public class AbstractRDFParserTest {

    private final RDF factory = new SimpleRDF();

    private final DummyRDFParserBuilder dummyParser = new DummyRDFParserBuilder();
    private Path testNt;
    private Path testTtl;
    private Path testXml;

	private Path symlink;

    @Before
    public void createTempFile() throws IOException {
        testNt = Files.createTempFile("test", ".nt");
        testTtl = Files.createTempFile("test", ".ttl");
        testXml = Files.createTempFile("test", ".xml");
        // No need to populate the files as the dummy parser
        // doesn't actually read anything

        // If supported, we'll make a symbolic link
        final Path symlinks = Files.createTempDirectory("symlinked");
        try {
        	symlink = Files.createSymbolicLink(
        				symlinks.resolve("linked.ttl"), testNt);
        } catch (IOException|UnsupportedOperationException ex) {
        	symlink = null;
        }
    }

    @After
    public void deleteTempFiles() throws IOException {
        Files.deleteIfExists(testNt);
        Files.deleteIfExists(testTtl);
        Files.deleteIfExists(testXml);
    }

    @Test
    public void guessRDFSyntax() throws Exception {
        assertEquals(RDFSyntax.NTRIPLES, AbstractRDFParser.guessRDFSyntax(testNt).get());
        assertEquals(RDFSyntax.TURTLE, AbstractRDFParser.guessRDFSyntax(testTtl).get());
        assertFalse(AbstractRDFParser.guessRDFSyntax(testXml).isPresent());
    }

    private void checkGraph(final Graph graph) throws Exception {
        assertFalse(graph.isEmpty());
        final IRI greeting = factory.createIRI("http://example.com/greeting");
        // Should only have parsed once!
        assertEquals(1, graph.stream(null, greeting, null).count());
        final Triple triple = graph.stream(null, greeting, null).findAny().get();
        assertTrue(triple.getSubject() instanceof IRI);
        final IRI parsing = (IRI) triple.getSubject();
        assertTrue(parsing.getIRIString().startsWith("urn:uuid:"));

        assertEquals("http://example.com/greeting", triple.getPredicate().getIRIString());

        assertTrue(triple.getObject() instanceof Literal);
        final Literal literal = (Literal) triple.getObject();
        assertEquals("Hello world", literal.getLexicalForm());
        assertFalse(literal.getLanguageTag().isPresent());
        assertEquals(Types.XSD_STRING, literal.getDatatype());

        // Check uniqueness of properties that are always present
        assertEquals(1, graph.stream(null, factory.createIRI("http://example.com/source"), null).count());

        // Check optional properties that are unique
        assertTrue(2 > graph.stream(null, factory.createIRI("http://example.com/base"), null).count());
        assertTrue(2 > graph.stream(null, factory.createIRI("http://example.com/contentType"), null).count());
        assertTrue(2 > graph.stream(null, factory.createIRI("http://example.com/contentTypeSyntax"), null).count());
    }

    @Test
    public void parseFile() throws Exception {
        try (final Graph g = factory.createGraph()) {
            final RDFParser parser = dummyParser.source(testNt).target(g);
            parser.parse().get(5, TimeUnit.SECONDS);
            checkGraph(g);
            // FIXME: this could potentially break if the equivalent of /tmp
            // includes
            // international characters
            assertEquals("<" + testNt.toUri().toString() + ">", firstPredicate(g, "source"));
            // Should be set to the file path - after following symlinks
            assertEquals("<" + testNt.toRealPath().toUri().toString() + ">", firstPredicate(g, "base"));

            // Should NOT have guessed the content type
            assertNull(firstPredicate(g, "contentType"));
            assertNull(firstPredicate(g, "contentTypeSyntax"));
        }
    }

    @Test
    public void parseFileSymlink() throws Exception {
        // This test will typically not work in Windows
        // which requires system privileges to create symlinks
        assumeNotNull(symlink);
        try (final Graph g = factory.createGraph()) {
            final RDFParser parser = dummyParser.source(symlink).target(g);
            parser.parse().get(5, TimeUnit.SECONDS);
            checkGraph(g);
            assertEquals("<" + symlink.toUri().toString() + ">", firstPredicate(g, "source"));
            assertEquals("<" + testNt.toRealPath().toUri().toString() + ">", firstPredicate(g, "base"));
        }
    }

    @Test
    public void parseNoSource() throws Exception {
        thrown.expect(IllegalStateException.class);
        dummyParser.parse();
    }

    @Test
    public void parseBaseAndContentTypeNoSource() throws Exception {
        // Can set the other options, even without source()
        final IRI base = dummyParser.createRDFTermFactory().createIRI("http://www.example.org/test.rdf");
        final RDFParser parser = dummyParser.base(base).contentType(RDFSyntax.RDFXML);
        thrown.expect(IllegalStateException.class);
        thrown.expectMessage("No source has been set");
        // but .parse() should fail
        parser.parse();
    }

    @Test
    public void parseFileMissing() throws Exception {
        Files.delete(testNt);
        // This should not fail yet
        final RDFParser parser = dummyParser.source(testNt);
        // but here:
        thrown.expect(IOException.class);
        parser.parse();
    }

    @Test
    public void parseFileContentType() throws Exception {
        try (final Graph g = factory.createGraph()) {
            final RDFParser parser = dummyParser.source(testNt).contentType(RDFSyntax.NTRIPLES).target(g);
            parser.parse().get(5, TimeUnit.SECONDS);
            checkGraph(g);
            // FIXME: this could potentially break if the equivalent of /tmp
            // includes
            // international characters
            assertEquals("<" + testNt.toUri().toString() + ">", firstPredicate(g, "source"));
            // Should be set to the file path - after following symlinks
            assertEquals("<" + testNt.toRealPath().toUri().toString() + ">", firstPredicate(g, "base"));
            assertEquals("\"" + RDFSyntax.NTRIPLES.name() + "\"", firstPredicate(g, "contentTypeSyntax"));
            assertEquals("\"application/n-triples\"", firstPredicate(g, "contentType"));
        }
    }

    private String firstPredicate(final Graph g, final String pred) {
        return g.stream(null, factory.createIRI("http://example.com/" + pred), null).map(Triple::getObject)
                .map(RDFTerm::ntriplesString).findAny().orElse(null);
    }

    @Rule
    public ExpectedException thrown = ExpectedException.none();

    @Test
    public void parseInputStreamFailsIfBaseMissing() throws Exception {
        final InputStream inputStream = new ByteArrayInputStream(new byte[0]);
        // Should not fail at this point
        final RDFParser parser = dummyParser.source(inputStream);
        // but here:
        thrown.expect(IllegalStateException.class);
        thrown.expectMessage("base iri required for inputstream source");
        parser.parse();
    }

    @Test
    public void parseInputStreamWithBase() throws Exception {
        final InputStream inputStream = new ByteArrayInputStream(new byte[0]);
        final IRI base = dummyParser.createRDFTermFactory().createIRI("http://www.example.org/test.rdf");
        try (final Graph g = factory.createGraph()) {
            final RDFParser parser = dummyParser.source(inputStream).base(base).target(g);
            parser.parse().get(5, TimeUnit.SECONDS);
            checkGraph(g);
            assertEquals("<http://www.example.org/test.rdf>", firstPredicate(g, "base"));
            // in our particular debug output,
            // bnode source indicates InputStream
            assertTrue(firstPredicate(g, "source").startsWith("_:"));
            assertNull(firstPredicate(g, "contentType"));
            assertNull(firstPredicate(g, "contentTypeSyntax"));
        }
    }

    @Test
    public void parseInputStreamWithNQuads() throws Exception {
        final InputStream inputStream = new ByteArrayInputStream(new byte[0]);
        try (final Graph g = factory.createGraph()) {
            final RDFParser parser = dummyParser.source(inputStream).contentType(RDFSyntax.NQUADS).target(g);
            parser.parse().get(5, TimeUnit.SECONDS);
            checkGraph(g);
            assertNull(firstPredicate(g, "base"));
            // in our particular debug output,
            // bnode source indicates InputStream
            assertTrue(firstPredicate(g, "source").startsWith("_:"));
            assertEquals("\"application/n-quads\"", firstPredicate(g, "contentType"));
            assertEquals("\"" + RDFSyntax.NQUADS.name() + "\"", firstPredicate(g, "contentTypeSyntax"));
        }
    }

    @Test
    public void parseIRI() throws Exception {
        final IRI iri = dummyParser.createRDFTermFactory().createIRI("http://www.example.net/test.ttl");
        try (final Graph g = factory.createGraph()) {
            final RDFParser parser = dummyParser.source(iri).target(g);
            parser.parse().get(5, TimeUnit.SECONDS);
            checkGraph(g);
            assertEquals("<http://www.example.net/test.ttl>", firstPredicate(g, "source"));
            // No base - assuming the above IRI is always
            // the base would break server-supplied base from
            // any HTTP Location redirects and Content-Location header
            assertNull(firstPredicate(g, "base"));
            // ".ttl" in IRI string does not imply any content type
            assertNull(firstPredicate(g, "contentType"));
            assertNull(firstPredicate(g, "contentTypeSyntax"));
        }
    }

    @Test
    public void parseIRIBaseContentType() throws Exception {
        final IRI iri = dummyParser.createRDFTermFactory().createIRI("http://www.example.net/test.ttl");
        try (final Graph g = factory.createGraph()) {
            final RDFParser parser = dummyParser.source(iri).base(iri).contentType(RDFSyntax.TURTLE).target(g);
            parser.parse().get(5, TimeUnit.SECONDS);
            checkGraph(g);
            assertEquals("<http://www.example.net/test.ttl>", firstPredicate(g, "source"));
            assertEquals("<http://www.example.net/test.ttl>", firstPredicate(g, "base"));
            assertEquals("\"" + RDFSyntax.TURTLE.name() + "\"", firstPredicate(g, "contentTypeSyntax"));
            assertEquals("\"text/turtle\"", firstPredicate(g, "contentType"));
        }
    }

}