diff --git a/lib/elife_parser/text.rb b/lib/elife_parser/text.rb
index 7391519..cbf7ad8 100644
--- a/lib/elife_parser/text.rb
+++ b/lib/elife_parser/text.rb
@@ -3,7 +3,16 @@ class Text
     attr_reader :content
 
     def initialize content
-      @content = content
+      @content = Text.validate_content_type(content)
+    end
+
+    # Check content type and raise exception if it isn't a String.
+    def self.validate_content_type(content)
+      unless content.is_a? String
+        raise ArgumentError, 'Invalid content type'
+      end
+
+      content
     end
 
     def sanitized_text
@@ -47,7 +56,7 @@ def modified_text_with_plus
         
         final_text = final_text.gsub(/\.+[\s+\$]/, " ")
         
-        # remove white spaces
+        # reduce white spaces
         final_text.gsub(/\s\s+/, "\s")
       end
     end
diff --git a/spec/elife_parser/text_spec.rb b/spec/elife_parser/text_spec.rb
index 50f7efd..9749d9b 100644
--- a/spec/elife_parser/text_spec.rb
+++ b/spec/elife_parser/text_spec.rb
@@ -9,10 +9,57 @@
     end
   end
 
+  describe "Text creation" do
+
+    # Helper function to create and test Text with given content.
+    def create_and_check_text(content)
+      text = described_class.new(content)
+
+      expect(text.is_a? ElifeParser::Text).to eq(true)
+      expect(text.content).to eq(content)
+    end
+
+    it "returns Text for valid content type" do
+      # Normal text
+      create_and_check_text('some text.')
+
+      # Text with especial characters.
+      create_and_check_text('@some #text')
+
+      # Only blank spaces.
+      create_and_check_text('      ')
+
+      # Only special characters.
+      create_and_check_text('@@@&&&###')
+    end
+
+    it "returns failure message for invalid content type" do
+      expect { described_class.new(3) }.to raise_error(ArgumentError, 'Invalid content type')
+      expect { described_class.new(:hello) }.to raise_error(ArgumentError, 'Invalid content type')
+      expect { described_class.new(["some text"]) }.to raise_error(ArgumentError, 'Invalid content type')
+      expect { described_class.new({name: "David"}) }.to raise_error(ArgumentError, 'Invalid content type')
+    end
+  end
+
   describe "modified_text_without_special_caracters" do
+
+    # TODO: refactor this test to only remove @ and #.
     it "should remove @ and #" do
-      expect(subject.modified_text_without_special_caracters).to eql(" manoel quirino ")
+      text = described_class.new("@manoel #quirino")
+      expect(text.modified_text_without_special_caracters).to eql(" manoel quirino ")
+
+      text = described_class.new("@manoel 🔥& #quirino")
+      expect(text.modified_text_without_special_caracters).to eql(" manoel :fire: & quirino ")
     end
+
+    # # Correct tests.
+    # it "should remove @ and #", :aggregate_failures do
+    #   text = described_class.new("@manoel #quirino")
+    #   expect(text.modified_text_without_special_caracters).to eql("manoel quirino")
+
+    #   text = described_class.new("@manoel 🔥& #quirino")
+    #   expect(text.modified_text_without_special_caracters).to eql("manoel 🔥& quirino")
+    # end
   end
 
   describe "modified_text" do
@@ -20,11 +67,10 @@
       expect(described_class.new("@livia.vilaca ##opa/&eba 🔥 🐷🐽.$ :?  .$ - -a º ρε👽😀☂❤华み원❤")
         .modified_text).to eql(" @livia.vilaca ##opa/&eba :fire: :pig: :pig_nose: a ρε :alien: :grinning: :heart: :heart: ")
     end
+
     it "should parse unicode heart and convert hearts" do
       expect(described_class.new("❤️ e 🔥 e ❤")
         .modified_text).to eql(" :heart: e :fire: e :heart: ")
     end
   end
-
-
 end