A Java JUnit test demonstrating an expression language query which will return true if and only if all attributes enumerated are not empty (i.e. not null, zero-length, or all whitespace characters).

noneEmptyELTest.java

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 * 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
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 *     http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.nifi.attribute.expression.language;

import org.antlr.runtime.tree.Tree;
import org.apache.nifi.attribute.expression.language.Query.Range;
import org.apache.nifi.attribute.expression.language.evaluation.QueryResult;
import org.apache.nifi.attribute.expression.language.exception.AttributeExpressionLanguageException;
import org.apache.nifi.attribute.expression.language.exception.AttributeExpressionLanguageParsingException;
import org.apache.nifi.expression.AttributeExpression.ResultType;
import org.apache.nifi.flowfile.FlowFile;
import org.junit.Assert;
import org.junit.Ignore;
import org.junit.Test;
import org.mockito.Mockito;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Locale;
import java.util.Map;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

public class TestQuery {
    
   @Test
    public void testShouldEvaluateEmptyAttributes() {
        /* This test came from a mailing list comment requesting notEmpty()
        *
        * This expression should return true IFF all attributes are:
        * - not null
        * - not empty (zero length String)
        * - not consisting entirely of whitespace characters
        * */

        // Arrange
        
        // This map of attributes has all "empty" elements
        final Map<String, String> emptyAttributes = new HashMap<>();
        emptyAttributes.put("attr1", "");
        emptyAttributes.put("attr2", null);
        emptyAttributes.put("attr3", "  ");

        // This map has some populated and some "empty" elements
        final Map<String, String> semiPopulatedAttributes = new HashMap<>();
        semiPopulatedAttributes.put("attr1", "test");
        semiPopulatedAttributes.put("attr2", "");
        semiPopulatedAttributes.put("attr3", " ");

        // This map has every element populated
        final Map<String, String> populatedAttributes = new HashMap<>();
        populatedAttributes.put("attr1", "test");
        populatedAttributes.put("attr2", "for");
        populatedAttributes.put("attr3", "Paul");

        // Act
        String anyEmptyQuery = "${anyAttribute(\"attr1\", \"attr2\", \"attr3\"):isEmpty()}";
        String noneEmptyQuery = "${allAttributes(\"attr1\", \"attr2\", \"attr3\"):isEmpty():not()}";

        // Assert
        verifyEquals(anyEmptyQuery, emptyAttributes, true);
        verifyEquals(noneEmptyQuery, emptyAttributes, false);

        verifyEquals(anyEmptyQuery,  semiPopulatedAttributes, true);
        verifyEquals(noneEmptyQuery, semiPopulatedAttributes, false);

        verifyEquals(anyEmptyQuery,  populatedAttributes, false);
        verifyEquals(noneEmptyQuery, populatedAttributes, true);
    }

    private void verifyEquals(final String expression, final Map<String, String> attributes, final Object expectedResult) {
        Query.validateExpression(expression, false);
        assertEquals(String.valueOf(expectedResult), Query.evaluateExpressions(expression, attributes, null));

        final Query query = Query.compile(expression);
        final QueryResult<?> result = query.evaluate(attributes);

        if (expectedResult instanceof Number) {
            assertEquals(ResultType.NUMBER, result.getResultType());
        } else if (expectedResult instanceof Boolean) {
            assertEquals(ResultType.BOOLEAN, result.getResultType());
        } else {
            assertEquals(ResultType.STRING, result.getResultType());
        }

        assertEquals(expectedResult, result.getValue());
    }
}