Execute maven goal on a submodule

I'm working on a html2pdf (GitHub project) customization. So I've downloaded the source code and I've imported it into the Eclipse Oxygen. I'm trying to execute the tests of this project, but every maven goal I run has no effect on the project. Yet, I've tried to execute the command explained here (To run tests), but nothing has happened.

So, my newbie question is: How can I run the tests of this project?

Here is the pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <parent>
    <groupId>com.itextpdf</groupId>
    <artifactId>root</artifactId>
    <version>7.1.2-SNAPSHOT</version>
    <relativePath />
  </parent>

  <artifactId>html2pdf</artifactId>
  <version>2.0.2-SNAPSHOT</version>

  <name>pdfHTML</name>
  <description>pdfHTML is an iText 7 add-on that lets you to parse (X)HTML snippets and the associated CSS and converts
    them to PDF.</description>
  <url>http://itextpdf.com/</url>

  <properties>
    <itext.version>${project.parent.version}</itext.version>
    <javadoc.version>3.0.0</javadoc.version>
  </properties>

  <repositories>
    <repository>
      <snapshots>
        <enabled>true</enabled>
      </snapshots>
      <id>itext-snapshot</id>
      <name>iText Repository - snapshots</name>
      <url>https://repo.itextsupport.com/snapshot</url>
    </repository>
    <repository>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
      <id>itext-releases</id>
      <name>iText Repository - releases</name>
      <url>https://repo.itextsupport.com/releases</url>
    </repository>
  </repositories>

  <dependencies>
    <dependency>
      <groupId>com.itextpdf</groupId>
      <artifactId>forms</artifactId>
      <version>${itext.version}</version>
    </dependency>
    <dependency>
      <groupId>com.itextpdf</groupId>
      <artifactId>layout</artifactId>
      <version>${itext.version}</version>
    </dependency>
    <dependency>
      <groupId>com.itextpdf</groupId>
      <artifactId>hyph</artifactId>
      <version>${itext.version}</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>com.itextpdf</groupId>
      <artifactId>pdfa</artifactId>
      <version>${itext.version}</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>com.itextpdf</groupId>
      <artifactId>pdftest</artifactId>
      <version>${itext.version}</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <resources>
      <resource>
        <directory>src/main/java</directory>
        <includes>
          <include>**/*.properties</include>
        </includes>
      </resource>
      <resource>
        <directory>src/main/resources</directory>
        <includes>
          <include>**/*.css</include>
          <include>**/*.ttf</include>
        </includes>
      </resource>
    </resources>
    <plugins>
      <plugin>
        <groupId>external.atlassian.jgitflow</groupId>
        <artifactId>jgitflow-maven-plugin</artifactId>
        <version>1.0-m5.1</version>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-failsafe-plugin</artifactId>
        <version>2.19.1</version>
        <configuration>
          <includes>
            <include>**/*Test.java</include>
          </includes>
          <groups>${integrationtests}</groups>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-javadoc-plugin</artifactId>
        <version>${javadoc.version}</version>
        <executions>
          <execution>
            <id>attach-javadocs</id>
            <goals>
              <goal>jar</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <quiet>true</quiet>
          <failOnError>true</failOnError>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-source-plugin</artifactId>
        <version>3.0.1</version>
        <executions>
          <execution>
            <id>attach-sources</id>
            <phase>verify</phase>
            <goals>
              <goal>jar-no-fork</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-surefire-plugin</artifactId>
        <version>2.19.1</version>
        <configuration>
          <groups>${unittests}</groups>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.pitest</groupId>
        <artifactId>pitest-maven</artifactId>
        <version>1.1.11</version>
        <configuration>
          <skip>true</skip>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.revapi</groupId>
        <artifactId>revapi-maven-plugin</artifactId>
        <version>0.8.2</version>
        <configuration>
          <skip>true</skip>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>