Add a ruby source code syntax test with source and output

tests/syntax-tests/source/Ruby/output.rb

@@ -0,0 +1,56 @@
+class RepeatedSubstring
+  def find_repeated_substring(s)
+    # catch the edge cases
+    return 'NONE' if s == ''
+    # check if the string consists of only one character => "aaaaaa" => "a"
+    return s.split('').uniq[0] if s.split('').uniq.length == 1
+
+    searched = []
+    longest_prefix = 0
+    long_prefix = ''
+    (0..s.length - 1).each do |i|
+      next if searched.include? s[i]
+
+      searched.push(s[i])
+      next_occurrences = next_index(s, i + 1, s[i])
+      next_occurrences.each do |next_occurrence|
+        next if next_occurrence == -1
+
+        prefix = ge_prefix(s[i..next_occurrence - 1], s[next_occurrence..s.length])
+        if prefix.length > longest_prefix
+          longest_prefix = prefix.length
+          long_prefix = prefix
+        end
+      end
+    end
+    # if prefix == "       " it is a invalid sequence
+    return 'NONE' if long_prefix.strip.empty?
+
+    long_prefix
+  end
+
+  def get_prefix(s1, s2)
+    prefix = ''
+    min_length = [s1.length, s2.length].min
+    return '' if s1.nil? || s2.nil?
+
+    (0..min_length - 1).each do |i|
+      return prefix if s1[i] != s2[i]
+
+      prefix += s1[i]
+    end
+    prefix
+  end
+
+  def next_index(seq, index, value)
+    indexes = []
+    (index..seq.length).each do |i|
+      indexes.push(i) if seq[i] == value
+    end
+    indexes
+  end
+
+  def find_repeated_substring_file(file_path)
+    File.open(file_path).read.each_line.map { |line| find_repeated_substring(line) }
+  end
+end