src/test/main/TestJsonParser.java

package main;

import org.codehaus.jackson.*;

import java.io.IOException;

/**
 * Set of basic unit tests for verifying that the basic parser
 * functionality works as expected.
 */
public class TestJsonParser
    extends BaseTest
{

    /**
     * This basic unit test verifies that example given in the Json
     * specification (RFC-4627 or later) is properly parsed at
     * high-level, without verifying values.
     */
    public void testSpecExampleSkipping()
        throws Exception
    {
        doTestSpec(false);
    }

    /**
     * Unit test that verifies that the spec example JSON is completely
     * parsed, and proper values are given for contents of all
     * events/tokens.
     */
    public void testSpecExampleFully()
        throws Exception
    {
        doTestSpec(true);
    }

    /**
     * Unit test that verifies that 3 basic keywords (null, true, false)
     * are properly parsed in various contexts.
     */
    public void testKeywords()
        throws Exception
    {
        final String DOC = "{\n"
            +"\"key1\" : null,\n"
            +"\"key2\" : true,\n"
            +"\"key3\" : false,\n"
            +"\"key4\" : [ false, null, true ]\n"
            +"}"
            ;

        JsonParser jp = createParserUsingStream(DOC, "UTF-8");
        assertToken(JsonToken.START_OBJECT, jp.nextToken());

        assertToken(JsonToken.FIELD_NAME, jp.nextToken());
        verifyFieldName(jp, "key1");
        assertToken(JsonToken.VALUE_NULL, jp.nextToken());

        assertToken(JsonToken.FIELD_NAME, jp.nextToken());
        verifyFieldName(jp, "key2");
        assertToken(JsonToken.VALUE_TRUE, jp.nextToken());

        assertToken(JsonToken.FIELD_NAME, jp.nextToken());
        verifyFieldName(jp, "key3");
        assertToken(JsonToken.VALUE_FALSE, jp.nextToken());

        assertToken(JsonToken.FIELD_NAME, jp.nextToken());
        verifyFieldName(jp, "key4");
        assertToken(JsonToken.START_ARRAY, jp.nextToken());
        assertToken(JsonToken.VALUE_FALSE, jp.nextToken());
        assertToken(JsonToken.VALUE_NULL, jp.nextToken());
        assertToken(JsonToken.VALUE_TRUE, jp.nextToken());
        assertToken(JsonToken.END_ARRAY, jp.nextToken());

        assertToken(JsonToken.END_OBJECT, jp.nextToken());
    }

    public void testInvalidKeywords()
        throws Exception
    {
        doTestInvalidKeyword1("nul");
        doTestInvalidKeyword2("nulla", JsonToken.VALUE_NULL);
        doTestInvalidKeyword1("fal");
        doTestInvalidKeyword3("False");
        doTestInvalidKeyword2("falsett0", JsonToken.VALUE_FALSE);
        doTestInvalidKeyword1("tr");
        doTestInvalidKeyword1("truE");
        doTestInvalidKeyword2("trueenough", JsonToken.VALUE_TRUE);
    }

    /*
    /////////////////////////////////////////////
    // Helper methods
    /////////////////////////////////////////////
    */

    private void doTestSpec(boolean verify)
        throws IOException
    {
        // First, using a StringReader:
        doTestSpecIndividual(null, verify);

        // Then with streams using supported encodings:
        doTestSpecIndividual("UTF-8", verify);
        doTestSpecIndividual("UTF-16BE", verify);
        doTestSpecIndividual("UTF-16LE", verify);

        /* Hmmh. UTF-32 is harder only because JDK doesn't come with
         * a codec for it. Can't test it yet using this method
         */
        //doTestSpecIndividual("UTF-32", verify);
    }

    private void doTestSpecIndividual(String enc, boolean verify)
        throws IOException
    {
        String doc = SAMPLE_DOC_JSON_SPEC;
        JsonParser jp;

        if (enc == null) {
            jp = createParserUsingReader(doc);
        } else {
            jp = createParserUsingStream(doc, enc);
        }

        assertToken(JsonToken.START_OBJECT, jp.nextToken()); // main object

        assertToken(JsonToken.FIELD_NAME, jp.nextToken()); // 'Image'
        if (verify) {
            verifyFieldName(jp, "Image");
        }

        assertToken(JsonToken.START_OBJECT, jp.nextToken()); // 'image' object

        assertToken(JsonToken.FIELD_NAME, jp.nextToken()); // 'Width'
        if (verify) {
            verifyFieldName(jp, "Width");
        }

        assertToken(JsonToken.VALUE_NUMBER_INT, jp.nextToken());
        if (verify) {
            verifyIntValue(jp, SAMPLE_SPEC_VALUE_WIDTH);
        }

        assertToken(JsonToken.FIELD_NAME, jp.nextToken()); // 'Height'
        if (verify) {
            verifyFieldName(jp, "Height");
        }

        assertToken(JsonToken.VALUE_NUMBER_INT, jp.nextToken());
        verifyIntValue(jp, SAMPLE_SPEC_VALUE_HEIGHT);
        assertToken(JsonToken.FIELD_NAME, jp.nextToken()); // 'Title'
        if (verify) {
            verifyFieldName(jp, "Title");
        }
        assertToken(JsonToken.VALUE_STRING, jp.nextToken());
        assertEquals(SAMPLE_SPEC_VALUE_TITLE, getAndVerifyText(jp));
        assertToken(JsonToken.FIELD_NAME, jp.nextToken()); // 'Thumbnail'
        if (verify) {
            verifyFieldName(jp, "Thumbnail");
        }

        assertToken(JsonToken.START_OBJECT, jp.nextToken()); // 'thumbnail' object
        assertToken(JsonToken.FIELD_NAME, jp.nextToken()); // 'Url'
        if (verify) {
            verifyFieldName(jp, "Url");
        }
        assertToken(JsonToken.VALUE_STRING, jp.nextToken());
        if (verify) {
            assertEquals(SAMPLE_SPEC_VALUE_TN_URL, getAndVerifyText(jp));
        }
        assertToken(JsonToken.FIELD_NAME, jp.nextToken()); // 'Height'
        if (verify) {
            verifyFieldName(jp, "Height");
        }
        assertToken(JsonToken.VALUE_NUMBER_INT, jp.nextToken());
        verifyIntValue(jp, SAMPLE_SPEC_VALUE_TN_HEIGHT);
        assertToken(JsonToken.FIELD_NAME, jp.nextToken()); // 'Width'
        if (verify) {
            verifyFieldName(jp, "Width");
        }
        // Width value is actually a String in the example
        assertToken(JsonToken.VALUE_STRING, jp.nextToken());
        assertEquals(SAMPLE_SPEC_VALUE_TN_WIDTH, getAndVerifyText(jp));

        assertToken(JsonToken.END_OBJECT, jp.nextToken()); // 'thumbnail' object

        assertToken(JsonToken.FIELD_NAME, jp.nextToken()); // 'IDs'
        assertToken(JsonToken.START_ARRAY, jp.nextToken()); // 'ids' array
        assertToken(JsonToken.VALUE_NUMBER_INT, jp.nextToken()); // ids[0]
        verifyIntValue(jp, SAMPLE_SPEC_VALUE_TN_ID1);
        assertToken(JsonToken.VALUE_NUMBER_INT, jp.nextToken()); // ids[1]
        verifyIntValue(jp, SAMPLE_SPEC_VALUE_TN_ID2);
        assertToken(JsonToken.VALUE_NUMBER_INT, jp.nextToken()); // ids[2]
        verifyIntValue(jp, SAMPLE_SPEC_VALUE_TN_ID3);
        assertToken(JsonToken.VALUE_NUMBER_INT, jp.nextToken()); // ids[3]
        verifyIntValue(jp, SAMPLE_SPEC_VALUE_TN_ID4);
        assertToken(JsonToken.END_ARRAY, jp.nextToken()); // 'ids' array

        assertToken(JsonToken.END_OBJECT, jp.nextToken()); // 'image' object

        assertToken(JsonToken.END_OBJECT, jp.nextToken()); // main object
    }

    private void verifyFieldName(JsonParser jp, String expName)
        throws IOException
    {
        assertEquals(expName, jp.getText());
        assertEquals(expName, jp.getCurrentName());
    }

    private void verifyIntValue(JsonParser jp, long expValue)
        throws IOException
    {
        // First, via textual
        assertEquals(String.valueOf(expValue), jp.getText());
    }

    private void doTestInvalidKeyword1(String value)
        throws IOException
    {
        JsonParser jp = createParserUsingStream("{ \"key1\" : "+value+" }", "UTF-8");
        assertToken(JsonToken.START_OBJECT, jp.nextToken());
        assertToken(JsonToken.FIELD_NAME, jp.nextToken());
        try {
            jp.nextToken();
            fail("Expected an exception for malformed value keyword");
        } catch (JsonParseException jex) {
            verifyException(jex, "Unrecognized token");
        }
    }

    private void doTestInvalidKeyword2(String value, JsonToken firstValue)
        throws IOException
    {
        JsonParser jp = createParserUsingStream("{ \"key1\" : "+value+" }", "UTF-8");
        assertToken(JsonToken.START_OBJECT, jp.nextToken());
        assertToken(JsonToken.FIELD_NAME, jp.nextToken());
        assertToken(firstValue, jp.nextToken());
        try {
            jp.nextToken();
            fail("Expected an exception for malformed value keyword");
        } catch (JsonParseException jex) {
            verifyException(jex, "Unexpected character");
        }
    }

    private void doTestInvalidKeyword3(String value)
        throws IOException
    {
        JsonParser jp = createParserUsingStream("{ \"key1\" : "+value+" }", "UTF-8");
        assertToken(JsonToken.START_OBJECT, jp.nextToken());
        assertToken(JsonToken.FIELD_NAME, jp.nextToken());
        try {
            jp.nextToken();
            fail("Expected an exception for malformed value keyword");
        } catch (JsonParseException jex) {
            verifyException(jex, "expected a valid value");
        }
    }
}