ContributionChecker::InvalidCommitUrlError to the rescue

lib/contribution-checker.rb

@@ -1,2 +1,3 @@
 require "contribution-checker/version"
+require "contribution-checker/error"
 require "contribution-checker/checker"

lib/contribution-checker/checker.rb

@@ -46,12 +46,14 @@ def initialize(options = {})
     #   }
     # }
     def check
-      parts = URI.parse(@commit_url).path.split("/")
-      @nwo = "#{parts[1]}/#{parts[2]}"
-      @sha = parts[4]
-      @user = @client.user
+      @nwo, @sha = parse_commit_url @commit_url
+      begin
+        @commit = @client.commit @nwo, @sha
+      rescue Octokit::NotFound
+        raise ContributionChecker::InvalidCommitUrlError
+      end
       @repo = @client.repository @nwo
-      @commit = @client.commit @nwo, @sha
+      @user = @client.user
 
       @commit_in_valid_branch = commit_in_valid_branch?
       @commit_in_last_year = commit_in_last_year?
@@ -79,6 +81,20 @@ def check
       }
     end
 
+    # Parses the commit URL provided.
+    #
+    # @return [Array] URL parts: nwo, sha
+    def parse_commit_url(url)
+      begin
+        parts = URI.parse(@commit_url).path.split("/")
+        nwo = "#{parts[1]}/#{parts[2]}"
+        sha = parts[4]
+        return nwo, sha
+      rescue
+        raise ContributionChecker::InvalidCommitUrlError
+      end
+    end
+
     # Checks whether the commit is in a valid branch. A valid branch is defined
     # as either the default branch of the repository, or the gh-pages branch.
     #

lib/contribution-checker/error.rb

@@ -0,0 +1,10 @@
+module ContributionChecker
+
+  # Error class to help us rescue from invalid commit URL input.
+  class InvalidCommitUrlError < StandardError
+    def initialize
+      super "Invalid commit URL provided"
+    end
+  end
+
+end