ContentIdPredicate.java

package fr.sii.ogham.testing.assertion.filter;

import static java.util.Collections.list;

import java.util.function.Predicate;

import javax.mail.Header;
import javax.mail.MessagingException;
import javax.mail.Part;

/**
 * Predicate that matches the {@link Part} only if {@link Part#getAllHeaders()}
 * contains a {@code Content-ID} header that exactly matches the provided
 * Content-ID.
 * 
 * @author Aurélien Baudet
 *
 */
public class ContentIdPredicate implements Predicate<Part> {
    private final String contentId;

    public ContentIdPredicate(String contentId) {
        super();
        this.contentId = contentId;
    }

    @Override
    public boolean test(Part input) {
        try {
            // @formatter:off
            return list(input.getMatchingHeaders(new String[] { "Content-ID" }))
                    .stream()
                    .map(Header::getValue)
                    .anyMatch(contentId::equals);
            // @formatter:on
        } catch (MessagingException e) {
            throw new AssertionError("Failed to access message", e);
        }
    }

    @Override
    public String toString() {
        return "having Content-ID header '" + contentId + "'";
    }

}