Support incrementing existing versionCode using step

Description of the feature request

Reading through the documentation and the code for the steps-change-android-versioncode-and-versionname step, for setting up versionCode (I’m disregarding any logic for versionName in this request) you have to define a predefined value (or env variable) as a new value, or default to $BITRISE_BUILD_NUMBER. Even when used in conjunction with the version_code_offset property, it assumes that a valid new_version_code is set.

Use case / for what or how I would use it

My use case is that I would like the step to help me just increment the existing versionCode by the version_code_offset value. The step already parses the existing versionCode in the code, so it would be great to make new_version_code optional or to not break current default behavior, just accept '' (empty string) as input (so it doesn’t default to $BITRISE_BUILD_NUMBER when it’s undeclared) and just simply increase the current versionCode by the value set in new_version_code (if set, otherwise skip)

It is possible to do this today in two steps:

  - script@1:
      inputs:
        - content: >-
            envman add --key CURRENT_VERSION_CODE --value "$(grep -P
            'versionCode(?:\s|=)+(.*?)(?:\s|\/\/|$)' $PROJECT_LOCATION/$MODULE//build.gradle |
            awk '{ print $2}')"
      title: Temporary solution to get current versionCode
  - change-android-versioncode-and-versionname@1:
      inputs:
        - new_version_code: $CURRENT_VERSION_CODE
        - version_code_offset: 1
        - build_gradle_path: $BITRISE_SOURCE_DIR/$MODULE/build.gradle
      title: Update versionCode and versionName

But you get the idea – this is not ideal since we both parse the same regexp in two places instead of just doing it in one

Thanks for the #feature-request! We’ll keep an eye on the votes :wink: