ModuleHelper variables management (#2162)

* added metadata for variables in module helper

* adjustments

* added separate support for tracking changes

* rewrote the diff code

* added integration test for module_helper

* using ansible.module_utils.common.dict_transformations.dict_merge

* improved dependency management

* restore ModuleHelper to base classes of CmdStateModuleHelper

* added assertions to ensure the failing module name appears in the error messages

* added test code for state-based modules

* fixed test name

* renamed class to VarMeta

* small fixes

* fixes from the PR

* fixed VarDict.__set_attr__

* added VarDict.__getitem__()

* added changelog fragment

* adjustments per PR

* ModuleHelper.output is now aware of conflicting variable names

* Update plugins/module_utils/module_helper.py

Co-authored-by: Felix Fontein <felix@fontein.de>

Co-authored-by: Felix Fontein <felix@fontein.de>

tests/integration/targets/module_helper/tasks/main.yml

@@ -0,0 +1,3 @@
+- include_tasks: msimple.yml
+- include_tasks: mdepfail.yml
+- include_tasks: mstate.yml

tests/integration/targets/module_helper/tasks/mdepfail.yml

@@ -0,0 +1,14 @@
+- name: test failing dependency
+  mdepfail:
+    a: 123
+  ignore_errors: yes
+  register: result
+
+- name: assert failing dependency
+  assert:
+    that:
+      - result.failed is true
+      - '"Failed to import" in result.msg'
+      - '"nopackagewiththisname" in result.msg'
+      - '"ModuleNotFoundError:" in result.exception'
+      - '"nopackagewiththisname" in result.exception'

tests/integration/targets/module_helper/tasks/msimple.yml

@@ -0,0 +1,54 @@
+- name: test msimple 1
+  msimple:
+    a: 80
+  register: simple1
+
+- name: assert simple1
+  assert:
+    that:
+      - simple1.a == 80
+      - simple1.abc == "abc"
+      - simple1.changed is false
+      - simple1.value is none
+
+- name: test msimple 2
+  msimple:
+    a: 101
+  ignore_errors: yes
+  register: simple2
+
+- name: assert simple2
+  assert:
+    that:
+      - simple2.a == 101
+      - 'simple2.msg == "Module failed with exception: a >= 100"'
+      - simple2.abc == "abc"
+      - simple2.failed is true
+      - simple2.changed is false
+      - simple2.value is none
+
+- name: test msimple 3
+  msimple:
+    a: 2
+    b: potatoes
+  register: simple3
+
+- name: assert simple3
+  assert:
+    that:
+      - simple3.a == 2
+      - simple3.b == "potatoespotatoes"
+      - simple3.c == "NoneNone"
+      - simple3.changed is false
+
+- name: test msimple 4
+  msimple:
+    c: abc change
+  register: simple4
+
+- name: assert simple4
+  assert:
+    that:
+      - simple4.c == "abc change"
+      - simple4.abc == "changed abc"
+      - simple4.changed is true

tests/integration/targets/module_helper/tasks/mstate.yml

@@ -0,0 +1,79 @@
+- name: test mstate 1
+  mstate:
+    a: 80
+    b: banana
+    c: cashew
+    state: nop
+  register: state1
+
+- name: assert state1
+  assert:
+    that:
+      - state1.a == 80
+      - state1.b == "banana"
+      - state1.c == "cashew"
+      - state1.result == "abc"
+      - state1.changed is false
+
+- name: test mstate 2
+  mstate:
+    a: 80
+    b: banana
+    c: cashew
+  register: state2
+
+- name: assert state2
+  assert:
+    that:
+      - state2.a == 80
+      - state2.b == "banana"
+      - state2.c == "cashew"
+      - state2.result == "80bananacashew"
+      - state2.changed is true
+
+- name: test mstate 3
+  mstate:
+    a: 3
+    b: banana
+    state: b_x_a
+  register: state3
+
+- name: assert state3
+  assert:
+    that:
+      - state3.a == 3
+      - state3.b == "banana"
+      - state3.result == "bananabananabanana"
+      - state3.changed is true
+
+- name: test mstate 4
+  mstate:
+    a: 4
+    c: cashew
+    state: c_x_a
+  register: state4
+
+- name: assert state4
+  assert:
+    that:
+      - state4.a == 4
+      - state4.c == "cashew"
+      - state4.result == "cashewcashewcashewcashew"
+      - state4.changed is true
+
+- name: test mstate 5
+  mstate:
+    a: 5
+    b: foo
+    c: bar
+    state: both_x_a
+  register: state5
+
+- name: assert state5
+  assert:
+    that:
+      - state5.a == 5
+      - state5.b == "foo"
+      - state5.c == "bar"
+      - state5.result == "foobarfoobarfoobarfoobarfoobar"
+      - state5.changed is true