Add missing test-cases for option -D/--delimiter-special.

Also move insert_special_delimiter into a function so it can
be tested.

diceware/__init__.py

@@ -163,6 +163,24 @@ def insert_special_char(word, specials=SPECIAL_CHARS, rnd=None):
     char_list[rnd.choice(range(len(char_list)))] = rnd.choice(specials)
     return ''.join(char_list)
 
+def insert_special_delimiter(words, max_delimiter_chars,
+                             specials=SPECIAL_CHARS, rnd=None):
+    """Insert a char out of `specials` into `word`.
+
+    `rnd`, if passed in, will be used as a (pseudo) random number
+    generator. We use `.choice()` only.
+
+    Returns the modified word.
+    """
+    if rnd is None:
+        rnd = SystemRandom()
+    words = words[:]
+    lengths = list(range(1, max_delimiter_chars + 1))
+    for pos in range(len(words)-1, 0, -1):
+        num_chars = rnd.choice(lengths)  # choose number of chars to insert
+        deli = "".join(rnd.choice(specials) for j in range(num_chars))
+        words.insert(pos, deli)
+    return words
 
 def get_passphrase(options=None):
     """Get a diceware passphrase.
@@ -194,11 +212,7 @@ def get_passphrase(options=None):
     if options.caps:
         words = [x.capitalize() for x in words]
     if options.delimiter_special:
-        lengths = list(range(1, options.delimiter_special + 1))
-        for pos in range(len(words)-1, 0, -1):
-            l = rnd.choice(lengths)
-            deli = "".join(rnd.choice(SPECIAL_CHARS) for j in range(l))
-            words.insert(pos, deli)
+        words = insert_special_delimiter(words, options.delimiter_special)
         result = "".join(words)
     else:
         result = options.delimiter.join(words)

tests/test_diceware.py

@@ -9,7 +9,7 @@
 from diceware import (
     get_wordlists_dir, SPECIAL_CHARS, insert_special_char, get_passphrase,
     handle_options, main, __version__, print_version, get_random_sources,
-    get_wordlist_names
+    get_wordlist_names, insert_special_delimiter
     )
 
 
@@ -86,6 +86,15 @@ def test_handle_options_delimiter(self):
         options = handle_options(['-d', 'WOW'])
         assert options.delimiter == 'WOW'
 
+    def test_handle_options_delimiter_special(self):
+        # we can set number of special characters to be used as delimiter
+        options = handle_options([])
+        assert options.delimiter_special == 0
+        options = handle_options(['-D', '3'])
+        assert options.delimiter_special == 3
+        options = handle_options(['--delimiter-special', '1'])
+        assert options.delimiter_special == 1
+
     def test_handle_options_randomsource(self):
         # we can choose the source of randomness
         source_names = get_random_sources().keys()
@@ -244,6 +253,37 @@ def test_get_passphrase_delimiters(self):
         phrase = get_passphrase(options)
         assert " " in phrase
 
+    def test_get_passphrase_special_delimiter(self):
+        # delimiter_special overrules delemiter
+        options = handle_options(args=[])
+        options.delimiter = " "
+        options.delimiter_special = 2
+        phrase = get_passphrase(options)
+        assert " " not in phrase
+
+    def test_insert_special_delimiter(self):
+        # we can insert special chars between the words.
+        fake_rnd = FakeRandom()
+        fake_rnd.nums_to_draw = [1, 2, 1,  # (num of chars)-1, char-idx
+                                 0, 1,
+                                 2, 1, 2, 0]
+        words_in = ['aaa', 'bbb', 'ccc', 'ddd']
+        result1 = insert_special_delimiter(words_in, 3,
+                                           specials='!$&', rnd=fake_rnd)
+        assert result1 == ['aaa', '$&!', 'bbb', '$', 'ccc', '&$', 'ddd']
+        assert words_in == ['aaa', 'bbb', 'ccc', 'ddd']  # unchanges
+
+    def test_insert_special_delimiter_defaults(self):
+        # defaults are respected
+        words_in = ['aaa', 'bbb']
+        result1 = insert_special_delimiter(words_in, 2)
+        assert result1[0] == 'aaa'
+        assert result1[2] == 'bbb'
+        assert 1 <= len(result1[1]) <= 2
+        assert result1[1][0] in SPECIAL_CHARS
+        if len(result1[1]) == 2:
+            result1[1][1] in SPECIAL_CHARS
+
     def test_print_version(self, capsys):
         # we can print version infos
         print_version()