Check prerequisites in install.sh

install.sh

@@ -228,9 +228,26 @@ function installModules() {
   done
 }
 
+function isMacOS() {
+  autoload is-at-least
+  [ "`uname -s`" = Darwin ] || return
+  is-at-least "10.13" "`sw_vers -productVersion 2> /dev/null`"
+}
+
+function isPlistBuddyInstalled() {
+  test -x /usr/libexec/PlistBuddy && return
+  which PlistBuddy >&! /dev/null && return
+}
+
+function checkPrerequisites() {
+  isMacOS || { lop error 'This setup is only for macOS 10.13 and up.'; return 10 }
+  isPlistBuddyInstalled || { lop error 'This setup requires PlistBuddy to be either at /usr/libexec or in any of the PATH directories.'; return 11 }
+}
+
 function main() {
   ensureDocopts
   autoloadZShLib
+  checkPrerequisites || return
   eval "`docopts -f -V - -h - : "$@" <<- USAGE
 	Usage: $0 [options] [-m PATH]... [<module>...]
 	

spec/isMacOS_spec.sh

@@ -0,0 +1,40 @@
+Describe 'isMacOS'
+  Include ./install.sh
+  uname() {  [ "${1}" = -s ] && echo Darwin }
+
+  It 'returns failure if sw_vers is not installed'
+    sw_vers() { echo "zsh: command not found: sw_vers" >&2; return 127 }
+    When call isMacOS
+    The output should eq ''
+    The status should be failure
+  End
+
+  It 'returns failure if os version is below 10.13'
+    sw_vers() { echo "1.1" }
+    When call isMacOS
+    The output should eq ''
+    The status should be failure
+  End
+
+  It 'returns success if os version is 10.13'
+    sw_vers() { echo "10.13" }
+    When call isMacOS
+    The output should eq ''
+    The status should be success
+  End
+
+  It 'returns success if os version is above 10.13'
+    sw_vers() { echo "17.04" }
+    When call isMacOS
+    The output should eq ''
+    The status should be success
+  End
+
+  It 'returns failure if kernel name is not Darwin'
+    sw_vers() { echo "10.13" }
+    uname() {  [ "${1}" = -s ] && echo Linux }
+    When call isMacOS
+    The output should eq ''
+    The status should be failure
+  End
+End

spec/isPlistBuddyInstalled_spec.sh

@@ -0,0 +1,26 @@
+Describe 'isPlistBuddyInstalled'
+  Include ./install.sh
+
+  It 'returns success if PlistBuddy path exists' 
+    test() { [ "$1" = "-x" ] && return }
+    When call isPlistBuddyInstalled
+    The output should eq ''
+    The status should be success
+  End
+
+  It 'returns success if PlistBuddy is in PATH' 
+    test() { [ "$1" = "-x" ] && return 1 }
+    which() { [ "$1" = "PlistBuddy" ] && return }
+    When call isPlistBuddyInstalled
+    The output should eq ''
+    The status should be success
+  End
+
+  It 'returns failure if PlistBuddy neither is in Path nor at usual path' 
+    test() { [ "$1" = "-x" ] && return 1 }
+    which() { [ "$1" = "PlistBuddy" ] && return 1 }
+    When call isPlistBuddyInstalled
+    The output should eq ''
+    The status should be failure
+  End
+End