Support checking of test classes

[THausherr]

Our problem (see at https://issues.apache.org/jira/browse/PDFBOX-2891) is that we'd like test classes to be checked too. This was proposed before:
http://mojo.10943.n7.nabble.com/Fwd-animal-sniffer-for-maven-test-classes-td43156.html
I don't know if "binkley" ever followed up on his patch proposal. I built the plugin locally and used this pom:

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>animal-sniffer-maven-plugin</artifactId>
    <version>1.15-SNAPSHOT</version>
    <executions>
        <execution>
            <id>check-java-version</id>
            <phase>test</phase>
            <goals>
                <goal>check</goal>
            </goals>
            <configuration>
                <signature>
                    <groupId>org.codehaus.mojo.signature</groupId>
                    <artifactId>java15</artifactId>
                    <version>1.0</version>
                </signature>
            </configuration>
        </execution>
    </executions>
</plugin>

Here's the "bad" code:

package animalsnifferdemo;

import org.junit.Test;

public class MainTest
{
    @Test
    public void testMain()
    {
        String str = "huhu";
        boolean empty = str.isEmpty();
        System.out.println(empty);
    }
}

The error (the use of isEmpty() which is not supported by JDK5) was not detected.

[sharwell]

I was hoping to use this project as a way to finally move away from -bootclasspath (and requiring users to download a very old JDK), but until this issue is fixed that will not be possible.

[karianna]

Would love to see this resolved as well

[nmatt]

Ditto.

[famod]

@olamy I'd take a stab on this, but first we need to decide whether this should become a new mojo or not.

Since the usage site recommends <phase>test</phase>, we could simply extend the existing mojo instead of adding a new one.

[olamy]

@famod yes try that. sorry for long response time

[famod]

@olamy Please see PR #80. Thanks!

[THausherr]

I then built locally and my test code is detected. However I tried to use the snapshot on one of my projects and it failed. This code reproduces the problem:

import org.junit.Assert;
import org.junit.Test;


public class MainTest
{
    
    public MainTest()
    {
    }

    @Test
    public void testMainBad2()
    {
        int totalAmountRead = 10;
        Assert.assertEquals(10, totalAmountRead);
    }
}

I get

--- animal-sniffer-maven-plugin:1.19-SNAPSHOT:check (check-java-version) @ MavenAnimalSnifferTest ---
Checking unresolved references to org.codehaus.mojo.signature:java18:1.0
XXXX\MavenAnimalSnifferTest\src\test\java\com\mycompany\mavenanimalsniffertest\MainTest.java:NNN: Undefined reference: void org.junit.Assert.assertEquals(long, long)

here's the pom, this time all set for java 8:

<?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>
    <groupId>com.mycompany</groupId>
    <artifactId>MavenAnimalSnifferTest</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.hamcrest</groupId>
            <artifactId>hamcrest-core</artifactId>
            <version>1.3</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>
    
    <build>
        <plugins>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>animal-sniffer-maven-plugin</artifactId>
                <version>1.19-SNAPSHOT</version>
                <executions>
                    <execution>
                        <id>check-java-version</id>
                        <phase>test</phase>
                        <goals>
                            <goal>check</goal>
                        </goals>
                        <configuration>
                            <signature>
                                <groupId>org.codehaus.mojo.signature</groupId>
                                <artifactId>java18</artifactId>
                                <version>1.0</version>
                            </signature>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

[famod]

Confirmed. I get loads of such errors in https://github.com/vackosar/gitflow-incremental-builder

[famod]

Ok, first problem found! At least scope test is missing here: https://github.com/mojohaus/animal-sniffer/blob/master/animal-sniffer-maven-plugin/src/main/java/org/codehaus/mojo/animal_sniffer/maven/CheckSignatureMojo.java#L387-L388

That reduces the number of false negatives but it is not sufficient. Investigating...

[famod]

Ok, I found the second problem. I'll create another PR but that will take some time because I need to look at the enforcer rule and I'd also like to add a test.

@olamy Can we reopen this? Thanks.

[famod]

PR #81 should fix the false negatives.

[famod]

@THausherr This should now work as expected (built from master).

[THausherr]

Yes, thank you. I was able to successfully verify Apache PDFBox trunk, 2.0 branch and 1.8 branch.