[build] Properly error out when a dependency does not exist

We should print a message saying it's missing, not explode
because we couldn't invoke the binary.

1 files changed, 27 insertions, 11 deletions

diff --git a/dependency_checker.rb b/dependency_checker.rb
index cfc10b45f0..223a0321f9 100644
--- a/dependency_checker.rb
+++ b/dependency_checker.rb
@@ -1,5 +1,7 @@
 require 'pp'
 
+NOT_INSTALLED_VERSION="-1"
+
 XAMARIN_MAC_MIN_VERSION="2.3"
 XAMARIN_MAC_VERSION=lambda { product_version ("/Library/Frameworks/Xamarin.Mac.framework/Versions/Current/bin/mmp") }
 XAMARIN_MAC_URL="http://www.xamarin.com"
@@ -20,25 +22,39 @@ def compare_version(first, second)
 end
 
 def mono_version(binary)
-	actual_version = `#{binary} --version`
-	# Extract the version number from a string like this:
-	# 	`Mono JIT compiler version 4.2.0 (explicit/08b7103 Mon Aug 17 16:58:52 EDT 2015)`
-	actual_version = actual_version.split('version ')[1]
-	return actual_version.split(' ')[0]
+	if File.exist?("#{binary}")
+		actual_version = `#{binary} --version`
+		# Extract the version number from a string like this:
+		# 	`Mono JIT compiler version 4.2.0 (explicit/08b7103 Mon Aug 17 16:58:52 EDT 2015)`
+		actual_version = actual_version.split('version ')[1]
+		return actual_version.split(' ')[0]
+	else
+		return NOT_INSTALLED_VERSION
+	end
 end
 
 def product_version(binary)
-	version = `#{binary} --version`
-	return version.split(' ')[1]
+	if File.exist?("#{binary}")
+		version = `#{binary} --version`
+		return version.split(' ')[1]
+	else
+		return NOT_INSTALLED_VERSION
+	end
 end
 
 def check_product(product_min_version, product_version, product_url, product_name)
 	actual_version = product_version.call
-	retval = compare_version(actual_version, product_min_version)
-	if (retval < 0)
-		puts ""
+	if (actual_version == NOT_INSTALLED_VERSION)
+		puts "You do not have #{product_name} installed.".red
+		retval = -1
+	else
 		puts "Your installed #{product_name} (#{actual_version}) is too old, please use #{product_min_version} or newer".red
+		retval = compare_version(actual_version, product_min_version)
+	end
+
+	if (retval < 0)
 		puts "You can download it from #{product_url}".red
+		puts
 	end
 	return retval
 end
@@ -49,7 +65,7 @@ def check_monodevelop_dependencies()
 		check_product(XAMARIN_MAC_MIN_VERSION, XAMARIN_MAC_VERSION, XAMARIN_MAC_URL, "Xamarin.Mac")
 	]
 	if (result.min < 0)
-		raise RuntimeError
+		exit 1
 	end
 end