Finally got the tests running. :-)

features/mark-multiple-integration.feature

@@ -17,8 +17,9 @@ Feature: Mark multiple integration
     When I insert "This text contains the word text twice"
     And I select "text"
     And I press "C->"
-    And I press "C-g"
-    And I type "'"
+    And I switch to multiple-cursors mode
+    And I type "("
     And I press "M-f"
-    And I type "'"
-    Then I should see "This 'text' contains the word 'text' twice"
+    And I press "M-f"
+    And I type ")"
+    Then I should see "This (text contains) the word (text twice)"

features/multiple-cursors-core.feature

@@ -5,9 +5,30 @@ Feature: Multiple cursors core
 
   Scenario: Two cursors
     Given there is no region selected
-    When I insert "This text contains the word text thrice (text)"
+    When I insert "This text contains the word text twice"
+    And I select "text"
+    And I press "C->"
+    And I switch to multiple-cursors mode
+    Then I should have 2 cursors
+
+  Scenario: Three cursors
+    Given there is no region selected
+    When I insert:
+    """
+    This text contains the word text thrice, and
+    one of the instances of the word text is on the second line.
+    """
     And I select "text"
     And I press "C->"
     And I press "C->"
-    And I press "C-g"
+    And I switch to multiple-cursors mode
     Then I should have 3 cursors
+
+  Scenario: Exiting multiple-cursors mode with return
+    Given there is no region selected
+    When I insert "This text contains the word text twice"
+    And I select "text"
+    And I press "C->"
+    And I switch to multiple-cursors mode
+    And I press "<return>"
+    Then I should have one cursor

features/step-definitions/multiple-cursors-steps.el

@@ -1,16 +1,27 @@
 (And "^delete-selection-mode is active$"
      (lambda ()
-        (delete-selection-mode 1)))
+       (delete-selection-mode 1)))
 
 (defun is-extra-cursor-p (o)
-  (message "overlay-type: %S" (overlay-get o 'type))
   (eq (overlay-get o 'type) 'additional-cursor))
 
 (defun num-cursors ()
   (1+ (count-if 'is-extra-cursor-p
-            (overlays-in (point-min) (point-max)))))
+                (overlays-in (point-min) (point-max)))))
 
 (Then "^I should have \\([0-9]+\\) cursors$"
-       (lambda (num)
-         (assert (eq (string-to-number num) (num-cursors)) nil
-                 "Expected to have %s cursors, but was %d." num (num-cursors))))
+      (lambda (num)
+        (let ((actual (num-cursors)))
+          (assert (eq (string-to-number num) actual) nil
+                  "Expected to have %s cursors, but was %d." num actual))))
+
+(Then "^I should have one cursor$"
+      (lambda ()
+        (assert (not multiple-cursors-mode) nil
+                "Expected to have one cursor, but multiple-cursors-mode is still active.")
+        (assert (eq 1 (num-cursors)) nil
+                "Expected to have one cursor, but there are still fake cursor overlays.")))
+
+(And "^I switch to multiple-cursors mode$"
+     (lambda ()
+       (mc/switch-from-mark-multiple-to-cursors)))

features/support/env.el

@@ -14,6 +14,7 @@
 (require 'ert)
 
 (Before
+ (multiple-cursors-mode 0)
  (mm/clear-all)
  (global-set-key (kbd "C->") 'mark-next-like-this)
  (switch-to-buffer

multiple-cursors-core.el

@@ -144,7 +144,7 @@ cursors."
                    original-command
                    (get original-command 'mc--unsupported))
         (if (not (memq original-command mc--cmds))
-            (when (not (memq original-command mc--cmds-run-once))
+            (when (and original-command (not (memq original-command mc--cmds-run-once)))
               (message "Skipping %S" original-command))
           (mc/execute-command-for-all-fake-cursors original-command))))))
 
@@ -222,12 +222,13 @@ from being executed if in multiple-cursors-mode."
            (overlay-put cursor 'kill-ring-yank-pointer kill-ring-yank-pointer)))))))
 ;;----------------------------------------------------------------------------------------
 
-;; Commands to run only once (not yet in use)
+;; Commands to run only once (don't need to message about skipping it)
 (setq mc--cmds-run-once '(mark-next-like-this
                           save-buffer
                           undo
                           undo-tree-undo
-                          undo-tree-redo))
+                          undo-tree-redo
+                          mc/switch-from-mark-multiple-to-cursors))
 
 ;; Commands that should be mirrored by all cursors
 (setq mc--cmds '(mc/keyboard-quit