Maven circular dependency?

Question

If I add this to a POM will it create a circular dependency? I've tried it and that what seems to happen. There is something I'm not understanding here. Isn't the war file created at the end of the build.

 <dependency>
  <groupId>${project.groupId}</groupId>
  <artifactId>mywebapp</artifactId>
  <version>${project.version}</version>
  <type>war</type>
  <scope>provided</scope>
 </dependency>

My directory structure is root/functest, root/mywebapp.

Effective POM

    [INFO] Scanning for projects...
[INFO] Searching repository for plugin with prefix: 'help'.
[INFO] org.grails: checking for updates from tapestry.javaforge
[WARNING] *** CHECKSUM FAILED - Checksum failed on download: local = 'ee0f52bc37051384f078f9706be9445b550ee4a6'; remote = 'a535436f42caf1ba0f9372328d2920372f30c842' - RETRYING
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[INFO] org.apache.maven.plugins: checking for updates from tapestry.javaforge
[INFO] org.codehaus.mojo: checking for updates from tapestry.javaforge
[INFO] artifact org.apache.maven.plugins:maven-help-plugin: checking for updates from tapestry.javaforge
[INFO] ------------------------------------------------------------------------
[INFO] Building functional-tests
[INFO]    task-segment: [help:effective-pom] (aggregator-style)
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[INFO] [help:effective-pom]
[INFO] 
Effective POMs, after inheritance, interpolation, and profiles are applied:

<?xml version="1.0" encoding="UTF-8"?>
<!-- ====================================================================== -->
<!--                                                                        -->
<!-- Generated by Maven Help Plugin on 9/30/09 10:41 AM                     -->
<!-- See: http://maven.apache.org/plugins/maven-help-plugin/                -->
<!--                                                                        -->
<!-- ====================================================================== -->

<!-- ====================================================================== -->
<!--                                                                        -->
<!-- Effective POM for project 'com.mycompany:functest:pom:1.0-SNAPSHOT'    -->
<!--                                                                        -->
<!-- ====================================================================== -->

<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"&gt;
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <artifactId>myapp</artifactId>
    <groupId>com.mycompany</groupId>
    <version>1.0-SNAPSHOT</version>
  </parent>
  <groupId>com.mycompany</groupId>
  <artifactId>functest</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>pom</packaging>
  <name>functional-tests</name>
  <url>http://www.mycompany.com/functest&lt;/url&gt;
  <organization>
    <name>My Company Inc</name>
    <url>http://www.mycompany.com&lt;/url&gt;
  </organization>
  <developers>
    <developer>
      <id>john.doe</id>
      <name>John Doe</name>
      <email>[email protected]</email>
    </developer>
  </developers>
  <build>
    <sourceDirectory>C:\Documents and Settings\ric\AutoSmokeTest\steps\step7\functest\src\main\java</sourceDirectory>
    <scriptSourceDirectory>src/main/scripts</scriptSourceDirectory>
    <testSourceDirectory>C:\Documents and Settings\ric\AutoSmokeTest\steps\step7\functest\src\it</testSourceDirectory>
    <outputDirectory>C:\Documents and Settings\ric\AutoSmokeTest\steps\step7\functest\target\classes</outputDirectory>
    <testOutputDirectory>C:\Documents and Settings\ric\AutoSmokeTest\steps\step7\functest\target\test-classes</testOutputDirectory>
    <resources>
      <resource>
        <mergeId>resource-0</mergeId>
        <directory>C:\Documents and Settings\ric\AutoSmokeTest\steps\step7\functest\src\main\resources</directory>
      </resource>
    </resources>
    <testResources>
      <testResource>
        <mergeId>resource-1</mergeId>
        <directory>C:\Documents and Settings\ric\AutoSmokeTest\steps\step7\functest\src\test\resources</directory>
      </testResource>
    </testResources>
    <directory>C:\Documents and Settings\ric\AutoSmokeTest\steps\step7\functest\target</directory>
    <finalName>functest-1.0-SNAPSHOT</finalName>
    <pluginManagement>
      <plugins>
        <plugin>
          <artifactId>maven-antrun-plugin</artifactId>
          <version>1.3</version>
        </plugin>
        <plugin>
          <artifactId>maven-assembly-plugin</artifactId>
          <version>2.2-beta-2</version>
        </plugin>
        <plugin>
          <artifactId>maven-clean-plugin</artifactId>
          <version>2.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>2.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-dependency-plugin</artifactId>
          <version>2.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-deploy-plugin</artifactId>
          <version>2.4</version>
        </plugin>
        <plugin>
          <artifactId>maven-ear-plugin</artifactId>
          <version>2.3.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-ejb-plugin</artifactId>
          <version>2.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-install-plugin</artifactId>
          <version>2.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-jar-plugin</artifactId>
          <version>2.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-javadoc-plugin</artifactId>
          <version>2.5</version>
        </plugin>
        <plugin>
          <artifactId>maven-plugin-plugin</artifactId>
          <version>2.4.3</version>
        </plugin>
        <plugin>
          <artifactId>maven-rar-plugin</artifactId>
          <version>2.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-release-plugin</artifactId>
          <version>2.0-beta-8</version>
        </plugin>
        <plugin>
          <artifactId>maven-resources-plugin</artifactId>
          <version>2.3</version>
        </plugin>
        <plugin>
          <artifactId>maven-site-plugin</artifactId>
          <version>2.0-beta-7</version>
        </plugin>
        <plugin>
          <artifactId>maven-source-plugin</artifactId>
          <version>2.0.4</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.4.3</version>
        </plugin>
        <plugin>
          <artifactId>maven-war-plugin</artifactId>
          <version>2.1-alpha-2</version>
        </plugin>
      </plugins>
    </pluginManagement>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>2.0.2</version>
        <executions>
          <execution>
            <goals>
              <goal>testCompile</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <source>1.5</source>
          <target>1.5</target>
        </configuration>
      </plugin>
      <plugin>
        <artifactId>maven-surefire-plugin</artifactId>
        <version>2.4.3</version>
        <executions>
          <execution>
            <phase>integration-test</phase>
            <goals>
              <goal>test</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <suiteXmlFiles>
            <suiteXmlFile>src/it/testng.xml</suiteXmlFile>
          </suiteXmlFiles>
          <parallel>true</parallel>
          <threadCount>10</threadCount>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.codehaus.cargo</groupId>
        <artifactId>cargo-maven2-plugin</artifactId>
        <version>1.0.1-alpha-1</version>
        <executions>
          <execution>
            <id>start-container</id>
            <phase>pre-integration-test</phase>
            <goals>
              <goal>start</goal>
              <goal>deploy</goal>
            </goals>
            <configuration>
              <deployer>
                <deployables>
                  <deployable>
                    <groupId>com.mycompany</groupId>
                    <artifactId>mywebapp</artifactId>
                    <type>war</type>
                    <pingURL>http://localhost:8080/mywebapp/index.html&lt;/pingURL&gt;
                    <pingTimeout>300000</pingTimeout>
                    <properties>
                      <context>mywebapp</context>
                    </properties>
                  </deployable>
                </deployables>
              </deployer>
            </configuration>
          </execution>
          <execution>
            <id>stop-container</id>
            <phase>post-integration-test</phase>
            <goals>
              <goal>stop</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <wait>false</wait>
          <container>
            <containerId>tomcat5x</containerId>
            <zipUrlInstaller>
              <url>http://www.apache.org/dist/tomcat/tomcat-5/v5.5.28/bin/apache-tomcat-5.5.28.zip&lt;/url&gt;
              <installDir>${installDir}</installDir>
            </zipUrlInstaller>
            <output>C:\Documents and Settings\ric\AutoSmokeTest\steps\step7\functest\target/tomcat5x.log</output>
            <log>C:\Documents and Settings\ric\AutoSmokeTest\steps\step7\functest\target/cargo.log</log>
          </container>
          <configuration>
            <home>C:\Documents and Settings\ric\AutoSmokeTest\steps\step7\functest\target/tomcat5x/container</home>
            <properties>
              <cargo.logging>high</cargo.logging>
              <cargo.servlet.port>8080</cargo.servlet.port>
            </properties>
          </configuration>
        </configuration>
      </plugin>
      <plugin>
        <artifactId>maven-help-plugin</artifactId>
        <version>2.1</version>
      </plugin>
    </plugins>
  </build>
  <repositories>
    <repository>
      <releases>
        <enabled>false</enabled>
      </releases>
      <snapshots />
      <id>public-snapshots</id>
      <url>http://public-snapshots&lt;/url&gt;
    </repository>
    <repository>
      <releases />
      <snapshots />
      <id>openqa-releases</id>
      <url>http://nexus.openqa.org/content/repositories/releases&lt;/url&gt;
    </repository>
    <repository>
      <id>openqa</id>
      <url>http://maven.openqa.org&lt;/url&gt;
    </repository>
    <repository>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
      <id>central</id>
      <name>Maven Repository Switchboard</name>
      <url>http://repo1.maven.org/maven2&lt;/url&gt;
    </repository>
  </repositories>
  <pluginRepositories>
    <pluginRepository>
      <releases>
        <enabled>false</enabled>
      </releases>
      <snapshots />
      <id>public-snapshots</id>
      <url>http://public-snapshots&lt;/url&gt;
    </pluginRepository>
    <pluginRepository>
      <releases />
      <snapshots />
      <id>openqa-plugin</id>
      <url>http://nexus.openqa.org/content/repositories/releases&lt;/url&gt;
    </pluginRepository>
    <pluginRepository>
      <releases />
      <snapshots />
      <id>another-plugin</id>
      <url>http://repo1.maven.org/maven2&lt;/url&gt;
    </pluginRepository>
    <pluginRepository>
      <releases />
      <id>codehaus.snapshots</id>
      <url>http://snapshots.repository.codehaus.org/&lt;/url&gt;
    </pluginRepository>
    <pluginRepository>
      <id>mortbay.repo</id>
      <url>http://www.mortbay.org/maven2/snapshot&lt;/url&gt;
    </pluginRepository>
    <pluginRepository>
      <id>tapestry.javaforge</id>
      <url>http://howardlewisship.com/repository&lt;/url&gt;
    </pluginRepository>
    <pluginRepository>
      <releases>
        <updatePolicy>never</updatePolicy>
      </releases>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
      <id>central</id>
      <name>Maven Plugin Repository</name>
      <url>http://repo1.maven.org/maven2&lt;/url&gt;
    </pluginRepository>
  </pluginRepositories>
  <dependencies>
    <dependency>
      <groupId>com.mycompany</groupId>
      <artifactId>mywebapp</artifactId>
      <version>1.0-SNAPSHOT</version>
      <type>war</type>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>org.seleniumhq.selenium.server</groupId>
      <artifactId>selenium-server</artifactId>
      <version>1.0.1</version>
    </dependency>
    <dependency>
      <groupId>org.seleniumhq.selenium.client-drivers</groupId>
      <artifactId>selenium-java-client-driver</artifactId>
      <version>1.0.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.testng</groupId>
      <artifactId>testng</artifactId>
      <version>5.1</version>
      <classifier>jdk15</classifier>
      <scope>test</scope>
    </dependency>
  </dependencies>
  <reporting>
    <outputDirectory>C:\Documents and Settings\ric\AutoSmokeTest\steps\step7\functest\target/site</outputDirectory>
  </reporting>
</project>

[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESSFUL
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 3 seconds
[INFO] Finished at: Wed Sep 30 10:41:00 CEST 2009
[INFO] Final Memory: 7M/13M
[INFO] ------------------------------------------------------------------------

Answer 1

It will only create a cyclic dependency if mywebapp is dependent on functest (or transitively dependent on it). From the name I would guess that functest is a test component so no such dependency would exist.

As you've seen, it is valid to substitute properties into dependency declarations, Maven will fail the build if it does result in a cycle.

I guess your confusion around "Isn't the war file created at the end of the build." is because you expect the build to fail as functest is built before mywebapp? Remember that Maven has access to local and remote repositories, so the result of any previous build of mywebapp will be available in the repository. If this is the case, try deleting mywebapp from you local/remote repositories and I suspect you will see the build fail due to an unresolved dependency.

Answer 2

If I add this to a POM will it create a circular dependency?

If the pom you are referring to is the pom of the functest module, adding a dependency to the mywebapp module will create a circular dependency only if the mywebapp module already depends on the functest module (which should not be the case here) as stated by Rich in another answer.

I've tried it and that what seems to happen.

Are you sure? Is your multi-modules project well defined? Can you show us the parent pom? Can you provide the trace obtained when launching maven from the parent?

[...] Isn't the war file created at the end of the build?

Well... it depends on what you are doing.

If you are strictly following Automated Smoke Tests With Selenium, Cargo, TestNG and Maven, please note that the author is not really covering the multi-modules project setup (I'm not saying he's not doing it, I'm just saying he's not covering that part) but only the functional testing project setup. He always launch maven from the functest directory, never as a reactor from the parent pom, and the webapp deployed by cargo in the step 7 is treated like an "external" dependency.

Now, if you are developing your own webapp, building it prior to run functional tests on it really makes sense. Actually, this would be the "recommended" approach. In your case, be sure to declare mywebapp as a dependency of functest and to declare both projects as modules of the parent pom, i.e. something like that (if the parent pom is in a parent directory):

  ...
  <modules>
    <module>mywebapp</module>
    <module>functest</module>
  </modules>
  ...