Create separate install script for travis

.travis.yml

@@ -8,16 +8,11 @@ matrix:
       sudo: required
       dist: trusty
       env:
-        matrix:
-          - SWIFT_VERSION=swift-3.1
-          - SWIFT_VERSION=swift-3.0.2
+        - SWIFT_VERSIONS=(3.0.2 3.1)
 env:
   global:
     - LC_CTYPE=en_US.UTF-8
     - LANG=en_US.UTF-8
     - FRAMEWORK_NAME="RandomKit"
-    - SWIFTENV_INSTALL="https://gist.githubusercontent.com/kylef/5c0475ff02b7c7671d2a/raw/9f442512a46d7a2af7b850d65a7e9bd31edfb09b/swiftenv-install.sh"
-before_install:
-  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then gem install xcpretty -N; fi
-  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then eval "$(curl -sL $SWIFTENV_INSTALL)"; fi
+install: ./ci/install.sh
 script: ./ci/travis.sh

ci/install.sh

@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+
+set -e
+
+if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then
+    export SWIFTENV_ROOT="$HOME/.swiftenv"
+    git clone https://github.com/kylef/swiftenv.git "$SWIFTENV_ROOT"
+    export PATH="$SWIFTENV_ROOT/bin:$SWIFTENV_ROOT/shims:$PATH"
+
+    for version in "$SWIFT_VERSIONS"; do
+        swiftenv install "$version"
+    done
+elif [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
+    gem install xcpretty -N
+fi

ci/travis.sh

@@ -3,7 +3,12 @@
 set -e -o pipefail
 
 if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then
-    swift test
+    for version in "$SWIFT_VERSIONS"; do
+        swiftenv global "$version"
+        swiftenv version
+
+        swift test
+    done
 elif [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
     xcodebuild -version