diff --git a/plantuml-mode.el b/plantuml-mode.el
index 733f95c..4484810 100644
--- a/plantuml-mode.el
+++ b/plantuml-mode.el
@@ -340,8 +340,8 @@ Uses prefix (as PREFIX) to choose where to display it:
     (defvar plantuml-keywords-regexp (concat "^\\s *" (regexp-opt plantuml-keywords 'words)  "\\|\\(<\\|<|\\|\\*\\|o\\)\\(\\.+\\|-+\\)\\|\\(\\.+\\|-+\\)\\(>\\||>\\|\\*\\|o\\)\\|\\.\\{2,\\}\\|-\\{2,\\}"))
     (defvar plantuml-builtins-regexp (regexp-opt plantuml-builtins 'words))
     (defvar plantuml-preprocessors-regexp (concat "^\\s *" (regexp-opt plantuml-preprocessors 'words)))
-    (defvar plantuml-indent-regexp-start "^[ \t]*\\(\\(?:.*\\)?\s*\\(?:[<>.*a-z-|]+\\)?\s*\\(?:\\[[a-zA-Z]+\\]\\)?\s+if\\|alt\\|else\\|note\s+over\\|note\sas\s.*\\|note\s+\\(\\(?:\\(?:buttom\\|left\\|right\\|top\\)\\)\\)\\(?:\s+of\\)?\\|\\(?:class\\|enum\\|package\\)\s+.*{\\)")
-    (defvar plantuml-indent-regexp-end "^[ \t]*\\(endif\\|else\\|end\\|end\s+note\\|.*}\\)")
+    (defvar plantuml-indent-regexp-start "^[ \t]*\\(\\(?:.*\\)?\s*\\(?:[<>.*a-z-|]+\\)?\s*\\(?:\\[[a-zA-Z]+\\]\\)?\s+if\s+.*\\|loop\s+.*\\|group\s+.*\\|par\s*$\\|opt\s+.*\\|alt\s+.*\\|else\\|note\s+over\\|note\sas\s.*\\|note\s+\\(\\(?:\\(?:buttom\\|left\\|right\\|top\\)\\)\\)\\(?:\s+of\\)?\\|\\(?:class\\|enum\\|package\\|database\\)\s+.*{\\|activate\s+.+\\)")
+    (defvar plantuml-indent-regexp-end "^[ \t]*\\(endif\\|else\\|end\\|end\s+note\\|.*}\\|deactivate\s+.+\\)")
 
     (setq plantuml-font-lock-keywords
           `(
@@ -402,41 +402,39 @@ Uses prefix (as PREFIX) to choose where to display it:
   (defvar plantuml-indent-regexp-start)
   (defvar plantuml-indent-regexp-end)
   (save-excursion
-    (let ((relative-depth 0)
-          (bob-visited? nil))
+    (let ((relative-depth 0))
+      ;; current line
       (beginning-of-line)
-      (forward-line -1)
-      (while (and (>= relative-depth 0)
-                  (not bob-visited?))
-        (if (bobp)
-            (setq bob-visited? t))
+      (if (looking-at plantuml-indent-regexp-end)
+          (setq relative-depth (1- relative-depth)))
+
+      ;; from current line backwards to beginning of buffer
+      (while (not (bobp))
+        (forward-line -1)
         (if (looking-at plantuml-indent-regexp-end)
             (setq relative-depth (1- relative-depth)))
         (if (looking-at plantuml-indent-regexp-start)
-            (setq relative-depth (1+ relative-depth)))
-        (forward-line -1))
+            (setq relative-depth (1+ relative-depth))))
 
       (if (<= relative-depth 0)
           0
         relative-depth))))
 
 (defun plantuml-indent-line ()
-  "Indent the current line to its desired indentation level."
+  "Indent the current line to its desired indentation level.
+Restore point to same position in text of the line as before indentation."
   (interactive)
   ;; forward declare the lazy initialized constants
   (defvar plantuml-indent-regexp-start)
   (defvar plantuml-indent-regexp-end)
-  (let ((original-indentation (current-indentation)))
+  ;; store position of point in line measured from end of line
+  (let ((original-position-eol (- (line-end-position) (point))))
     (save-excursion
       (beginning-of-line)
-      (if (bobp)
-          (indent-line-to 0)
-        (let ((depth (plantuml-current-block-depth)))
-          (when (looking-at plantuml-indent-regexp-end)
-            (setq depth (max (1- depth) 0)))
-          (indent-line-to (* tab-width depth)))))
-    (forward-char (- (current-indentation)
-                     original-indentation))))
+      (indent-line-to (* tab-width (plantuml-current-block-depth))))
+
+    ;; restore position in text of line
+    (goto-char (- (line-end-position) original-position-eol))))
 
 
 ;;;###autoload
diff --git a/test/plantuml-indentation-test.el b/test/plantuml-indentation-test.el
index c8bc723..8791040 100644
--- a/test/plantuml-indentation-test.el
+++ b/test/plantuml-indentation-test.el
@@ -1,4 +1,4 @@
-;;; plantuml-mode-indentation-test.el --- PlantUML Mode indentation tests   -*- lexical-binding: t; -*-
+;;; plantuml-indentation-test.el --- PlantUML Mode indentation tests   -*- lexical-binding: t; -*-
 
 ;; Author: Raymond Huang (rymndhng)
 ;; Maintainer: Carlo Sciolla (skuro)
@@ -10,202 +10,499 @@
 
 ;;; Code:
 
-(defun add-text-and-position-cursor (txt)
-  "Add TXT into the buffer, move cursor to the position of the marker | and delete the marker."
+(defun plantuml-test-add-text-and-position-cursor (txt)
+  "Test helper for `plantuml-mode' tests.
+Add TXT into the buffer, move cursor to the position of the marker
+?| and delete the marker."
   (insert txt)
   (goto-char (point-min))
   (search-forward "|")
   (delete-char -1))
 
-(defun assert-block-depth (expected txt)
-  "Assert the EXPECTED indentation level for the given TXT."
+(defun plantuml-test-assert-block-depth (expected txt)
+  "Test helper for `plantuml-mode' tests.
+Assert the EXPECTED indentation level for the given TXT."
   (with-temp-buffer
-    (add-text-and-position-cursor txt)
+    (plantuml-test-add-text-and-position-cursor txt)
     (let ((actual (plantuml-current-block-depth)))
       (should (equal expected actual)))))
 
-(ert-deftest test-plantuml-current-block-depth ()
+(ert-deftest plantuml-test-current-block-depth_bob ()
+  "Test `plantuml-current-block-depth' level 0 at beginning of buffer."
   (setq-local plantuml-jar-path plantuml-test-jar-path)
   (plantuml-init-once)
 
-  (assert-block-depth 0 "
-A |-> B")
+  (plantuml-test-assert-block-depth 0 "|
+activate p1
+  activate p2
+    foo
+  deactivate p2
+deactivate p1
+")
+  )
 
-  (assert-block-depth 0 "
-pac|kage Foo {
-A -> B
-}")
+(ert-deftest plantuml-test-current-block-depth_0 ()
+  "Test `plantuml-current-block-depth' level 0 at beginning of first line."
+  (setq-local plantuml-jar-path plantuml-test-jar-path)
+  (plantuml-init-once)
 
-  (assert-block-depth 1 "
+  (plantuml-test-assert-block-depth 0 "
+|activate p1
+  activate p2
+    foo
+  deactivate p2
+deactivate p1
+")
+  )
+
+(ert-deftest plantuml-test-current-block-depth_1 ()
+  "Test `plantuml-current-block-depth' level 0 at middle of first line."
+  (setq-local plantuml-jar-path plantuml-test-jar-path)
+  (plantuml-init-once)
+
+  (plantuml-test-assert-block-depth 0 "
+acti|vate p1
+  activate p2
+    foo
+  deactivate p2
+deactivate p1
+")
+  )
+
+(ert-deftest plantuml-test-current-block-depth_2 ()
+  "Test `plantuml-current-block-depth' level 0 at end of first line"
+  (setq-local plantuml-jar-path plantuml-test-jar-path)
+  (plantuml-init-once)
+
+  (plantuml-test-assert-block-depth 0 "
+activate p1|
+  activate p2
+    foo
+  deactivate p2
+deactivate p1
+")
+  )
+
+(ert-deftest plantuml-test-current-block-depth_3 ()
+  "Test `plantuml-current-block-depth' level 1 at beginning of 2nd line."
+
+  (plantuml-test-assert-block-depth 1 "
+activate p1
+  |activate p2
+    foo
+  deactivate p2
+deactivate p1
+")
+  )
+
+(ert-deftest plantuml-test-current-block-depth_4 ()
+  "Test `plantuml-current-block-depth' level 2 at beginning of 3rd line."
+
+  (plantuml-test-assert-block-depth 2 "
+activate p1
+  activate p2
+    |foo
+  deactivate p2
+deactivate p1
+")
+  )
+
+(ert-deftest plantuml-test-current-block-depth_5 ()
+  "Test `plantuml-current-block-depth' level 1 at beginning of 4th line."
+
+  (plantuml-test-assert-block-depth 1 "
+activate p1
+  activate p2
+    foo
+  |deactivate p2
+deactivate p1
+")
+  )
+
+(ert-deftest plantuml-test-current-block-depth_6 ()
+  "Test `plantuml-current-block-depth' level 0 at beginning of 5th line."
+
+  (plantuml-test-assert-block-depth 0 "
+activate p1
+  activate p2
+    foo
+  deactivate p2
+|deactivate p1
+")
+  )
+
+(ert-deftest plantuml-test-current-block-depth_eob ()
+  "Test `plantuml-current-block-depth' level 0 at end of buffer."
+
+  (plantuml-test-assert-block-depth 0 "
+activate p1
+  activate p2
+    foo
+  deactivate p2
+deactivate p1
+|")
+  )
+
+(defun plantuml-test-indent-line (before after)
+  "The common code for the line indentation tests.
+
+BEFORE is the text to be inserted into a temporary buffer.
+AFTER is the expected text after indentation.
+
+Both, BEFORE and AFTER need to specify point with char |. The
+temporary buffer will be put into `plantuml-mode', the char |
+representing point will be removed from text. The line with the
+removed | will be indented (just this line!) with two spaces for each
+level of indentation.
+
+Finally,
+1) the indented line will be compared with the same line in AFTER
+2) the position of point in the indented line will be compared with
+the position of | in AFTER."
+
+  (let* ( (expected-cursor-pos (1+ (s-index-of "|" after)))
+          (expected-state (delete ?| after))
+          )
+    (with-temp-buffer
+      ;; fix the JAR location prior to mode initialization
+      ;; for some reason, plantuml-mode disregards the setq-local
+      (setq-local plantuml-jar-path plantuml-test-jar-path)
+      (plantuml-init-once)
+
+      (plantuml-test-add-text-and-position-cursor before)
+      (plantuml-mode)
+
+      ;; use 2 spaces instead of one tab for indentation
+      (setq-local indent-tabs-mode nil)
+      (setq-local tab-width 2)
+      (indent-according-to-mode)
+
+      (should (equal expected-state (buffer-string)))
+      (should (equal expected-cursor-pos (point))))))
+
+(ert-deftest plantuml-test-line-indentation/empty-line-l0 ()
+  "Test correct indentation of empty line - indentation level 0."
+  (plantuml-test-indent-line "|" "|"))
+
+(ert-deftest plantuml-test-line-indentation/bol-notindent-l0 ()
+  "Test correct indentation of a not indented line with point at beginning of line - indentation level 0."
+  (plantuml-test-indent-line "|participant A"
+                             "|participant A"))
+
+(ert-deftest plantuml-test-line-indentation/mol-notindent-l0 ()
+  "Test correct indentation of a not indented line with point at middle of line - indentation level 0."
+  (plantuml-test-indent-line "parti|cipant"
+                             "parti|cipant"))
+
+(ert-deftest plantuml-test-line-indentation/eol-notindent-l0 ()
+  "Test correct indentation of a not indented line with point at end of line - indentation level 0."
+  (plantuml-test-indent-line "participant A|"
+                             "participant A|"))
+
+(ert-deftest plantuml-test-line-indentation/bol-indented-l0 ()
+  "Test correct indentation of an indented line with point at beginning of line - indentation level 0."
+  (plantuml-test-indent-line "          |participant A"
+                             "|participant A"))
+
+(ert-deftest plantuml-test-line-indentation/mol-indented-l0 ()
+  "Test correct indentation of an indented line with point at middle of line - indentation level 0."
+  (plantuml-test-indent-line "          parti|cipant"
+                             "parti|cipant"))
+
+(ert-deftest plantuml-test-line-indentation/eol-indented-l0 ()
+  "Test correct indentation of an indented line with point at end of line - indentation level 0."
+  (plantuml-test-indent-line "          participant A|"
+                             "participant A|"))
+
+(ert-deftest plantuml-test-line-indentation/empty-line-l1 ()
+  "Test correct indentation of empty line - indentation level 1."
+  (plantuml-test-indent-line
+   "opt A
+|"
+   "opt A
+  |"))
+
+(ert-deftest plantuml-test-line-indentation/bol-notindent-l1 ()
+  "Test correct indentation of a not indented line with point at beginning of line - indentation level 1."
+  (plantuml-test-indent-line "opt A
+|foofoo"
+                             "opt A
+  |foofoo"))
+
+(ert-deftest plantuml-test-line-indentation/mol-notindent-l1 ()
+  "Test correct indentation of a not indented line with point at middle of line - indentation level 1."
+  (plantuml-test-indent-line "opt A
+foo|foo"
+                             "opt A
+  foo|foo"))
+
+(ert-deftest plantuml-test-line-indentation/eol-notindent-l1 ()
+  "Test correct indentation of a not indented line with point at end of line - indentation level 1."
+  (plantuml-test-indent-line "opt A
+foofoo|"
+                             "opt A
+  foofoo|"))
+
+(ert-deftest plantuml-test-line-indentation/bol-indented-l1 ()
+  "Test correct indentation of an indented line with point at beginning of line - indentation level 1."
+  (plantuml-test-indent-line "            opt A
+                              |foofoo"
+                             "            opt A
+  |foofoo"))
+
+(ert-deftest plantuml-test-line-indentation/mol-indented-l1 ()
+  "Test correct indentation of an indented line with point at middle of line - indentation level 1."
+  (plantuml-test-indent-line "   opt A
+                                        foo|foo"
+                             "   opt A
+  foo|foo"))
+
+(ert-deftest plantuml-test-line-indentation/eol-indented-l1 ()
+  "Test correct indentation of an indented line with point at end of line - indentation level 1."
+  (plantuml-test-indent-line "               opt A
+                                                          foofoo|"
+                             "               opt A
+  foofoo|"))
+
+
+(defun plantuml-test-indent-block (before after)
+  "The common code for the block indentation tests.
+
+BEFORE is the text block to be inserted into a temporary buffer.
+AFTER is the expected text block after indentation.
+
+The temporary buffer will be put into `plantuml-mode'. The whole buffer
+will be indented with two spaces for each level of indentation.
+
+Finally, the indented text in the buffer will be compared with AFTER."
+
+  (with-temp-buffer
+    ;; fix the JAR location prior to mode initialization
+    ;; for some reason, plantuml-mode disregards the setq-local
+    (setq-local plantuml-jar-path plantuml-test-jar-path)
+    (plantuml-init-once)
+
+    (insert before)
+    (goto-char (point-min))
+    (plantuml-mode)
+    ;; use 2 spaces instead of one tab for indentation
+    (setq-local indent-tabs-mode nil)
+    (setq-local tab-width 2)
+
+    (indent-region (point-min) (point-max))
+    (should (equal (buffer-string) after))
+    ))
+
+(ert-deftest plantuml-test-block-indentation/package-empty ()
+  "Test correct indentation of an empty package block."
+  (plantuml-test-indent-block
+   "
+package APackage ()
+"
+   "
+package APackage ()
+"))
+
+(ert-deftest plantuml-test-block-indentation/package ()
+  "Test correct indentation of a package block."
+  (plantuml-test-indent-block
+   "
 package APackage {
-|A -> B
-}")
+A -> B
+}
+"
+   "
+package APackage {
+  A -> B
+}
+"))
 
+(ert-deftest plantuml-test-block-indentation/package-database-nested ()
+  "Test correct indentation of two nested blocks, a package and a database.
+Note: currently the inner database is not indented."
+  (plantuml-test-indent-block
+   "
+package APackage {
+  database ADatabase {
+    A -> B
+  }
+}
+"
+   "
+package APackage {
+  database ADatabase {
+    A -> B
+  }
+}
+"))
 
-  (assert-block-depth 1 "
+(ert-deftest plantuml-test-block-indentation/alt-end ()
+  "Test correct indentation of an alt-end block."
+  (plantuml-test-indent-block
+   "
 alt choice 1
-|A -> B
+A -> B
+end
+"
+   "
+alt choice 1
+  A -> B
+end
+" ))
+
+(ert-deftest plantuml-test-block-indentation/alt-else-end ()
+  "Test correct indentation of an alt-else-end block."
+  (plantuml-test-indent-block
+   "
+alt choice 1
+A -> B
+else
+B -> C
+end
+"
+   "
+alt choice 1
+  A -> B
+else
+  B -> C
+end
+" ))
+
+(ert-deftest plantuml-test-block-indentation/opt ()
+  "Test correct indentation of an opt block."
+  (plantuml-test-indent-block
+   "
+opt event triggered
+A -> B
+end
+"
+   "
+opt event triggered
+  A -> B
+end
+" ))
+
+(ert-deftest plantuml-test-block-indentation/par ()
+  "Test correct indentation of a par block."
+  (plantuml-test-indent-block
+   "
+par
+A -> B
+else
+C -> B
+end
+"
+   "
+par
+  A -> B
+else
+  C -> B
+end
+" ))
+
+
+(ert-deftest plantuml-test-block-indentation/alt-else-loop-group ()
+  "Test correct indentation of combination of alt-else, loop and group.
+
+This is taken from the plantuml homepage."
+  (plantuml-test-indent-block
+   "
+Alice -> Bob: Authentication Request
+
+alt successful case
+
+Bob -> Alice: Authentication Accepted
+
+else some kind of failure
+
+Bob -> Alice: Authentication Failure
+group My own label
+Alice -> Log : Log attack start
+loop 1000 times
+Alice -> Bob: DNS Attack
+end
+Alice -> Log : Log attack end
+end
+
+else Another type of failure
+
+Bob -> Alice: Please repeat
+
+end
+"
+   "
+Alice -> Bob: Authentication Request
+
+alt successful case
+
+  Bob -> Alice: Authentication Accepted
+
+else some kind of failure
+
+  Bob -> Alice: Authentication Failure
+  group My own label
+    Alice -> Log : Log attack start
+    loop 1000 times
+      Alice -> Bob: DNS Attack
+    end
+    Alice -> Log : Log attack end
+  end
+
+else Another type of failure
+
+  Bob -> Alice: Please repeat
+
 end
 "))
 
-;; This is taken from https://github.com/clojure-emacs/clojure-mode/blob/master/test/clojure-mode-indentation-test.el
-(defmacro check-indentation (description before after &optional var-bindings)
-  "Declare an ert test for indentation behaviour.
-The test will check that the swift indentation command changes the buffer
-from one state to another.  It will also test that point is moved to an
-expected position.
-DESCRIPTION is a symbol describing the test.
-BEFORE is the buffer string before indenting, where a pipe (|) represents
-point.
-AFTER is the expected buffer string after indenting, where a pipe (|)
-represents the expected position of point.
-VAR-BINDINGS is an optional let-bindings list.  It can be used to set the
-values of customisable variables."
-  (declare (indent 1))
-  (let ((fname (intern (format "indentation/%s" description))))
-    `(ert-deftest ,fname ()
-       (let* ((after ,after)
-              (expected-cursor-pos (1+ (s-index-of "|" after)))
-              (expected-state (delete ?| after))
-              ,@var-bindings)
-         (with-temp-buffer
-           ;; fix the JAR location prior to mode initialization
-           ;; for some reason, plantuml-mode disregards the setq-local
-           (setq-local plantuml-jar-path plantuml-test-jar-path)
-           (plantuml-init-once)
 
-           (add-text-and-position-cursor ,before)
-           (plantuml-mode)
-
-           ;; use 2 spaces instead of one tab for indentation
-           (setq-local indent-tabs-mode nil)
-           (setq-local tab-width 2)
-           (indent-according-to-mode)
-
-           (should (equal expected-state (buffer-string)))
-           (should (equal expected-cursor-pos (point))))))))
-
-(check-indentation toplevel-relationship
-  "|Nobody -> [APIGateway]"
-  "|Nobody -> [APIGateway]")
-
-(check-indentation package-block
-                   "package APackage {
-|A -> B
-}"
-                   "package APackage {
-  |A -> B
-}")
-
-(check-indentation nested-package
-  "package APackage {
-|package AnotherPackage {
-}
-}"
-  "package APackage {
-  |package AnotherPackage {
-}
-}")
-
-(check-indentation empty-package
-  "|package Foo {}"
-  "|package Foo {}")
-
-(check-indentation relative-indent
-  "package APackage {
-database Foo
-|A --> B
-}
-}"
-  "package APackage {
-database Foo
-  |A --> B
-}
-}"
-  )
-
-(check-indentation note-as
-  "note as N1
-|This is a note
-end note"
-  "note as N1
-  |This is a note
-end note"
-  )
-
-(check-indentation note-of
-  "note right of Foo
-|This is a note
-end note"
-  "note right of Foo
-  |This is a note
-end note"
-  )
-
-(check-indentation alt
-  "alt choice 1
-|A -> B
-end
+(ert-deftest plantuml-test-block-indentation/note-as ()
+  "Test correct indentation of a note-as block."
+  (plantuml-test-indent-block
+   "
+note as N1
+This is a note
+end note
 "
-  "alt choice 1
-  |A -> B
-end
-")
-
-(check-indentation alt-end
-  "alt choice 1
-  A -> B
-|end
+   "
+note as N1
+  This is a note
+end note
 "
-  "alt choice 1
-  A -> B
-|end
-")
+   ))
 
-(check-indentation alt-else
-  "alt choice 1
-|else
-end
+(ert-deftest plantuml-test-block-indentation/activate-deactivate ()
+  "Test correct indentation of an activate-deactivate block."
+  (plantuml-test-indent-block
+   "
+activate participant_1
+participant_1 -> participant_2 : f()
+deactivate participant_1
 "
-  "alt choice 1
-|else
-end
-")
+   "
+activate participant_1
+  participant_1 -> participant_2 : f()
+deactivate participant_1
+"))
 
-(check-indentation alt-else-body
-  "alt choice 1
-else
-|A -> B
-end
+(ert-deftest plantuml-test-block-indentation/activate-deactivate-nested ()
+  "Test correct indentation of two nested activate-deactivate blocks."
+  (plantuml-test-indent-block
+   "
+activate participant_1
+activate participant_2
+participant_1 -> participant_2 : f()
+deactivate participant_2
+deactivate participant_1
 "
-  "alt choice 1
-else
-  |A -> B
-end
-")
-
-(check-indentation alt-else-end
-  "alt choice 1
-else
-|end
-"
-  "alt choice 1
-else
-|end
-")
-
-(check-indentation alt-else-body
-  "alt choice 1
-else
-|A -> B
-end
-"
-  "alt choice 1
-else
-  |A -> B
-end
-")
+   "
+activate participant_1
+  activate participant_2
+    participant_1 -> participant_2 : f()
+  deactivate participant_2
+deactivate participant_1
+"))
 
 (provide 'plantuml-indentation-test)
 
-;;; plantuml-mode-preview-test.el ends here
+;;; plantuml-indentation-test.el ends here