How to specify a build folder in Travis?

I have a github repository user/repo but the real project is in a subfolder user/repo/project/build.sbt
What should I write in the .travis.yml to make Travis ignore the top folder and work only in the project folder?

Inspired by this I tried the following which didn't work:

env:
  global:
    - REPO="user/repo"
    - CI_HOME=`pwd`/$REPO
script: sh -c 'cd $CI_HOME/project' && sbt ++$TRAVIS_SCALA_VERSION package

Error log:

$ sh -c 'cd $CI_HOME/project' && sbt ++$TRAVIS_SCALA_VERSION package
Detected sbt version 0.12.2-RC1
/home/travis/build/user/repo doesn't appear to be an sbt project.

Ideally there should be a way to specify the build folder but let Travis handle the build command.

You could also try adding the following line in your .travis.yml file:

before_script: cd project

I tried using this in my travis.yml file but didnt work

before_script: cd project

Then i tried this

before_install: cd project

And that worked 

Just write a shell script and use this to build your project. Make sure it works locally. Something like this should do the trick:

build.sh:

#!/bin/sh
cd $TRAVIS_BUILD_DIR/project
sbt ++$TRAVIS_SCALA_VERSION package

.travis.yml:

script: build.sh

Adding below on your .travis.yml file should do it:

before_script: cd <project_name>
script:
  - sbt compile
  - sbt test

In your yml file, add a "cd sub-folder" step, before you run the build command:

default:
- step:
script:
- cd project
- sbt ++$TRAVIS_SCALA_VERSION package

Example for gradle projects:

default:
- step:
script:
- cd project
- chmod +x gradlew
- ./gradlew assembleDebug

This will fix an error like "chmod: cannot access 'gradlew': No such file or directory", if the gradlew file is in a different folder to the git root.

It will also work in other build systems that use yml files, like bitbucket-pipelines.yml.