[SalesForce] Unable to deploy code to Sandbox as installed Managed Package test methods are failing

Edit: Summer '15 made this "all better". If you upgrade your ant-salesforce.jar to one that supports API version 34, you can now pass a "testLevel=RunLocalTests" attribute to sf:deploy like so:

<sf:deploy
  testLevel="RunLocalTests" 
  username="${sf.username}" 
  password="${sf.password}" 
  serverUrl="${sf.server}" 
  deployRoot="src" 
  />

From the docs:

http://releasenotes.docs.salesforce.com/en-us/summer15/release-notes/rn_deployment_run_subset_of_tests.htm

As part of this change, the runAllTests deployment option is now replaced with testLevel. You can choose which tests to run in a deployment by setting the desired test level. For a description of all test levels, see test levels for the deploy() call. In particular, to run a subset of tests in a deployment, set testLevel to the RunSpecifiedTests value and specify the tests to run in the runTests option.

And

http://releasenotes.docs.salesforce.com/en-us/summer15/release-notes/rn_api_meta_new_calls.htm#testlevels

RunLocalTests—All tests in your organization are run, except the ones that originate from installed managed packages. This test level is the default for production deployments that include Apex classes or triggers.

This was the workaround for pre-Summer '15 for posterity:

Because I killed off the better part of a day hacking around in ant to accomplish the workaround @pepefloyd suggested, I wanted to publish a working example; In my case, the test classes are prefixed with "Test_" but you can fool around with the fileset as necessary

This is tested against v30 of the Force.com ant migration tool

<target name="test">
    <sfCompileAndTestUnmanaged checkOnly="true" username="${sf.username}" password="${sf.password}" server="${sf.server}">
        <fileset dir="src/classes">
            <include name="**/Test_*.cls"/>
        </fileset>
    </sfCompileAndTestUnmanaged>
</target>

<scriptdef name="sfCompileAndTestUnmanaged" language="javascript">
    <attribute name="checkonly"/>
    <attribute name="username"/>
    <attribute name="password"/>
    <attribute name="server"/>
    <attribute name="trace"/>
    <element name="fileset" type="fileset"/>

    <![CDATA[
        var filesets = elements.get("fileset");
        var filesetsIterator = filesets.iterator();
        var projectClasses = [];
        while(filesetsIterator.hasNext()){
            var fs = filesetsIterator.next();
            var iter = fs.iterator();
            while(iter.hasNext()){
                var resource = iter.next();
                var clazz = resource.getName().replace(".cls","");
                self.log("CLASS: " + clazz);
                projectClasses.push(clazz);
            }
        }

        var task = project.createTask("antlib:com.salesforce:compileAndTest");
        task.setCheckonly(attributes.get("checkonly") == 'true');
        task.setUsername(attributes.get("username"));
        task.setPassword(attributes.get("password"));
        task.setServer(attributes.get("server"));
        task.setTrace(attributes.get("trace") == 'true');

        //I tried 'importPackage' and conventional instantiation but couldn't get the inner class to instantiate; this works though
        var testsElement = task.getClass().getClassLoader().loadClass("com.salesforce.ant.CompileAndTest$RunTestsElement").newInstance();
        task.addRunTests(testsElement);

        var classClazz = task.getClass().getClassLoader().loadClass("com.salesforce.ant.CompileAndTest$CodeNameElement");
        for(i in projectClasses){
            var clazz = classClazz.newInstance();
            clazz.addText(projectClasses[i]);
            testsElement.addClass(clazz);
        }

        task.execute();
     ]]>
</scriptdef>

Alternatively, we've actually used a version of 'deploy' that does a no-op deploy (the package.xml in the 'ant' directory is empty except for the <version> element. This gives us incremental updates as the tests are running and allows the deployment of the source files to succeed in a separate ant target (not described below) while the tests may fail (insufficient code coverage, failing assertions, etc.)

<target name="test">
    <sfDeployUnmanaged purgeOnDelete="true" ignoreWarnings="true" username="${sf.username}" password="${sf.password}" serverUrl="${sf.server}" deployRoot="ant" maxPoll="75">
        <fileset dir="src/classes">
            <include name="**/*.cls"/>
        </fileset>
    </sfDeployUnmanaged>
</target>

<scriptdef name="sfDeployUnmanaged" language="javascript">
    <attribute name="purgeondelete"/>
    <attribute name="ignorewarnings"/>
    <attribute name="username"/>
    <attribute name="password"/>
    <attribute name="serverurl"/>
    <attribute name="deployroot"/>
    <attribute name="maxpoll"/>
    <attribute name="trace"/>
    <element name="fileset" type="fileset"/>

    <![CDATA[
        var filesets = elements.get("fileset");
        var filesetsIterator = filesets.iterator();
        var projectClasses = [];
        while(filesetsIterator.hasNext()){
            var fs = filesetsIterator.next();
            var iter = fs.iterator();
            while(iter.hasNext()){
                var resource = iter.next();
                var clazz = resource.getName().replace(".cls","");
                self.log("CLASS: " + clazz);
                projectClasses.push(clazz);
            }
        }

        var task = project.createTask("antlib:com.salesforce:deploy");
        task.setPurgeOnDelete(attributes.get("purgeondelete") == 'true');
        task.setIgnoreWarnings(attributes.get("ignorewarnings") == 'true');
        task.setUsername(attributes.get("username"));
        task.setPassword(attributes.get("password"));
        task.setServerURL(attributes.get("serverurl"));
        task.setDeployRoot(attributes.get("deployroot"));
        task.setMaxPoll(attributes.get("maxpoll"));
        task.setTrace(attributes.get("trace") == 'true');

        //Blows up when build timeout is reached if we don't set this (it uses this value when formatting the exception it throws)
        task.setOwningTarget(self.owningTarget);

        var classClazz = task.getClass().getClassLoader().loadClass("com.salesforce.ant.DeployTask$CodeNameElement");
        for(i in projectClasses){
            var clazz = classClazz.newInstance();
            clazz.addText(projectClasses[i]);
            task.addRunTest(clazz);
        }

        task.execute();
     ]]>
</scriptdef>

After inspecting the deleted components tab within the managed package, it was discovered that a certain class AaaClass was listed when it should not have. We looked at our src directory and discovered that we were in fact trying to deploy the AaaClass file. Once we 'undeleted' the AaaClass from the deleted components tab in the managed package and attempted to redeploy, the error messages went away.

Unfortunately, this type of vague error was misleading and not at all indicative of what the actual issue was. Only by chance did we notice that there was a file in the deleted components that should not have been there. Hopefully, this helps anyone else who might come across this issue.