Resolve "Unit tests unter Windows"

Summary

100% tests passed, 0 tests failed out of 108

Related to #77 (closed) and #72 (closed)

Focus

Point the reviewer to the core of the code change. Where should they start reading? What should they focus on (e.g. security, performance, maintainability, user-friendliness, compliance with the specs, finding more corner cases, concrete questions)?

Test Environment

How to set up a test environment for manual testing?

Check List for the Author

Please, prepare your MR for a review. Be sure to write a summary and a focus and create gitlab comments for the reviewer. They should guide the reviewer through the changes, explain your changes and also point out open questions. For further good practices have a look at our review guidelines

• All automated tests pass
• Reference related issues
• Up-to-date CHANGELOG.md (or not necessary)
• Up-to-date JSON schema (or not necessary)
• Appropriate user and developer documentation (or not necessary)
  • How do I use the software? Assume "stupid" users.
  • How do I develop or debug the software? Assume novice developers.
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md (or not necessary)
• Appropriate user and developer documentation (or not necessary)
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there specifications? Are they satisfied?

For further good practices have a look at our review guidelines.

include/linkahead/configuration.h

@@ -103,10 +103,8 @@ public:
  */
 class ConfigurationManager {
 public:
-  static ConfigurationManager &GetInstance() {
-    static ConfigurationManager instance;
-    return instance;
-  };
+  static ConfigurationManager &GetInstance();
+  ;
 
   /**
    * See mReset.
@@ -156,6 +154,7 @@ public:
 private:
   Arena arena;
   JsonValue json_configuration;
+  static ConfigurationManager mInstance;
 
   inline ConfigurationManager()
     : json_configuration(nullptr){