Update the Caesar to be case-insensitive and skip unknown symbols.

src/cipher_analytical_machine/caesar.clj

@@ -14,21 +14,28 @@
        (+ key)
        (mod max-index)))
 
+(defn encrypt-or-skip
+  "If symbols do not have a character, then it will be skipped."
+  [index character key symbols max-index]
+  (if (nil? index) character
+      (get symbols
+           (encrypt-index index key max-index))))
+
 (defn encrypt-char
   "Calculates new index of a character. Uses a char from symbols, the key and max-index (exclusive)."
   [char key symbols max-index]
-  (get symbols
   (-> char
       (calculate-char-index symbols)
-           (encrypt-index key max-index))))
+      (encrypt-or-skip char key symbols max-index)))
 
 (defn encrypt-message
-  "Encrypt a message using the Caesar cipher."
+  "Encrypt a message using the Caesar cipher. The function is case-insensitive."
   [message key symbols]
   (let [max-index (count symbols)]
-    (cs/join
-     (map (fn [char] (encrypt-char char key symbols max-index))
-          message))))
+    (->> message
+         (cs/lower-case)
+         (map (fn [char] (encrypt-char char key symbols max-index)))
+         (cs/join))))
 
 (defn decrypt-message
   "Decrypt the ciphtext using the Caesar cipher."

test/cipher_analytical_machine/caesar_test.clj

@@ -51,14 +51,20 @@
     (testing "The message 'abc' is encrypted to 'bca'"
       (is (= "bca" (encrypt-message "abc" 1 symbols))))
 
+    (testing "The message 'ABC' is encrypted to 'bca', because of case-insensitive."
+      (is (= "bca" (encrypt-message "ABC" 1 symbols))))
+
     (testing "The message 'bca' is decrypted to 'abc'"
       (is (= "abc" (encrypt-message "bca" -1 symbols))))))
 
 (deftest decrypt-message-text
   (let [symbols "abc"]
     (testing "The message 'bca' is decrypted to 'abc'"
-      (is (= "abc" (decrypt-message "bca" 1 symbols)))
+      (is (= "abc" (decrypt-message "bca" 1 symbols))))
+
+    (testing "The message 'BCA' is decrypted to 'abc', because of case-insensitive."
+      (is (= "abc" (decrypt-message "BCA" 1 symbols))))
 
     (testing "The message 'abc' is encrypted to 'bca'"
-      (is (= "bca" (decrypt-message "abc" -1 symbols)))))))
+      (is (= "bca" (decrypt-message "abc" -1 symbols))))))