<target name="runAllTests">
  <sf:deploy username="${username}" password="${password}"
      serverurl="${serverurl}" deployroot="${root}"
      checkonly="true" testLevel="RunAllTestsInOrg" />
</target>

sfdx force:apex:test:run [-u usernameOrAlias]
   [-s TestSuites | -n ClassNames | -t TestMethods | -l TestLevel ]