I’m posting in order to help future readers, you need to add these dependencies for powermock in AS
testImplementation 'junit:junit:4.12'
testImplementation 'org.powermock:powermock-api-mockito:1.6.2'
testImplementation 'org.powermock:powermock-module-junit4-rule-agent:1.6.2'
testImplementation 'org.powermock:powermock-module-junit4-rule:1.6.2'
testImplementation 'org.powermock:powermock-module-junit4:1.6.2'