AssertJ has a lot of custom assertion methods for different types. For example to assert an URL object AssertJ gives us some specific methods. We can check for different components of the URL instance with different methods. For example we can check if the protocol is equal to the protocol we expect with hasProtocol(String). Similarly we can write assertions for the host, port, authority, path and anchor. To assert query parameters we can use hasQueryParameter(String) to check if query parameter is set and with hasQueryParameter(String, String) we can check if the query parameter has an expected value. To check the whole query string we can use hasQueryString(String).

Each of the assertion methods also has version to assert a component is not present. For example hasNoQuery() to assert a query is not defined for an URL.

In the following example we use the different assertion methods for an URL instance:

package mrhaki;

import org.junit.jupiter.api.Test;

import java.net.MalformedURLException;
import java.net.URL;

import static org.assertj.core.api.Assertions.assertThat;

class UrlChecks {

    @Test
    void checkUrl() throws MalformedURLException {
        assertThat(new URL("https://www.mrhaki.com:80/blogs/index.html#groovy-goodness"))

                // We can check the protocol.
                .hasProtocol("https")

                // We can check the host name.
                .hasHost("www.mrhaki.com")

                // We can check the port if it is part of the URL.
                .hasPort(80)

                // We can check the authority (host + port).
                .hasAuthority("www.mrhaki.com:80")

                // We can check the path part of the URL.
                .hasPath("/blogs/index.html")

                // We can check the anchor part.
                .hasAnchor("groovy-goodness");
    }

    @Test
    void checkQueryParameters() throws MalformedURLException {
        assertThat(new URL("https://www.mrhaki.com/blogs/?tag=Groovy&text=Goodness"))

                // We can check the full query string.
                .hasQuery("tag=Groovy&text=Goodness")

                // We can check if a query parameter is defined.
                .hasParameter("tag")
                .hasParameter("text")

                // We can check if a query parameter with a given value is set.
                .hasParameter("tag", "Groovy")
                .hasParameter("text", "Goodness")

                // We can verify with another URL after the query parameters are sorted.
                .isEqualToWithSortedQueryParameters(new URL("https://www.mrhaki.com/blogs/?text=Goodness&tag=Groovy"));
    }

    @Test
    void checkUserInfo() throws MalformedURLException {
        assertThat(new URL("https://user:password@www.mrhaki.com/"))

                // We can check the user info part of the URL.
                .hasUserInfo("user:password");
    }

    @Test
    void checkUrlNegated() throws MalformedURLException {
        // We can also check for the non-presence of components of the URL.
        assertThat(new URL("https://www.mrhaki.com"))
                .hasNoPort()
                .hasNoPath()
                .hasNoQuery()
                .hasNoParameters()
                .hasNoParameter("tag")
                .hasNoParameter("tag", "Groovy")
                .hasNoAnchor()
                .hasNoUserInfo();

        assertThat(new URL("file:///Users/mrhaki"))
                .hasNoHost();
    }
}

Written with AssertJ 3.24.2.

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