chore: rewrite unit tests and fix bugs for charm_state module (#278)

* rewrite unit tests and fix bugs for charm_state module

* fix typo

* make lint happy

* add private endpoint args to make tests pass

* fix typo

* add missing opts

* fix logger exception

src-docs/charm_state.py.md

@@ -116,7 +116,7 @@ Some charm configurations are grouped into other configuration models.
 
 ---
 
-<a href="../src/charm_state.py#L419"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/charm_state.py#L380"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>classmethod</kbd> `check_reconcile_interval`
 
@@ -145,7 +145,7 @@ Validate the general charm configuration.
 
 ---
 
-<a href="../src/charm_state.py#L375"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/charm_state.py#L407"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>classmethod</kbd> `from_charm`
 
@@ -225,7 +225,7 @@ The charm state.
 
 ---
 
-<a href="../src/charm_state.py#L855"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/charm_state.py#L867"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>classmethod</kbd> `from_charm`
 
@@ -369,7 +369,7 @@ Return a string representing the path.
 ## <kbd>class</kbd> `ImmutableConfigChangedError`
 Represents an error when changing immutable charm state. 
 
-<a href="../src/charm_state.py#L787"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/charm_state.py#L799"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>function</kbd> `__init__`
 
@@ -415,7 +415,7 @@ Return the aproxy address.
 
 ---
 
-<a href="../src/charm_state.py#L659"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/charm_state.py#L644"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>classmethod</kbd> `check_use_aproxy`
 
@@ -445,7 +445,7 @@ Validate the proxy configuration.
 
 ---
 
-<a href="../src/charm_state.py#L621"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/charm_state.py#L672"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>classmethod</kbd> `from_charm`
 
@@ -486,7 +486,7 @@ Runner configurations for the charm.
 
 ---
 
-<a href="../src/charm_state.py#L572"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/charm_state.py#L527"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>classmethod</kbd> `check_virtual_machine_resources`
 
@@ -517,7 +517,7 @@ Validate the virtual_machine_resources field values.
 
 ---
 
-<a href="../src/charm_state.py#L550"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/charm_state.py#L505"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>classmethod</kbd> `check_virtual_machines`
 
@@ -546,7 +546,7 @@ Validate the virtual machines configuration value.
 
 ---
 
-<a href="../src/charm_state.py#L500"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/charm_state.py#L559"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>classmethod</kbd> `from_charm`
 
@@ -609,7 +609,7 @@ SSH connection information for debug workflow.
 
 ---
 
-<a href="../src/charm_state.py#L747"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/charm_state.py#L758"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>classmethod</kbd> `from_charm`
 
@@ -642,7 +642,7 @@ Raised when given machine charm architecture is unsupported.
 
  - <b>`arch`</b>:  The current machine architecture. 
 
-<a href="../src/charm_state.py#L704"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/charm_state.py#L715"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>function</kbd> `__init__`