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>
My guess is that your deployment manifest is missing the Pricebook2 custom object.
I was able to successfully create an external id text field named New__c on the Pricebook2 object in a developer org by making a metadata api deployment with the following contents:
./package.xml
<?xml version="1.0" encoding="UTF-8"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
<types>
<members>Pricebook2</members>
<name>CustomObject</name>
</types>
<version>36.0</version>
</Package>
./objects/Pricebook2.object
<?xml version="1.0" encoding="UTF-8"?>
<CustomObject xmlns="http://soap.sforce.com/2006/04/metadata">
<fields>
<fullName>New__c</fullName>
<externalId>true</externalId>
<label>New</label>
<length>5</length>
<required>false</required>
<trackTrending>false</trackTrending>
<type>Text</type>
<unique>false</unique>
</fields>
</CustomObject>
I got an error message that said Pricebook2.New__c was not in package.xml when deploying:
./package.xml
<?xml version="1.0" encoding="UTF-8"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
<types>
<name>CustomObject</name>
</types>
<version>36.0</version>
</Package>
./objects/Pricebook2.object
<!-- Same as above -->
Best Answer
In the Setup UI you will see that custom fields (that are presented for Task) are added under the "Activities" heading and this is also reflected in the package.xml that the Ant tools use.
So your package.xml will need entries like these:
where Activity is used for your custom fields and Task is used for standard fields such as Subject (whose picklist values you might want to customise).