1. A method for asynchronous code testing in an Integrated Development Environment (IDE), said method comprising: creating, by a processor of a computer system that hosts the IDE, an input code based on inputs provided by a user; said processor storing the input code in a database coupled to the computer system, said input code comprising a plurality of code blocks organized in a hierarchy of nesting levels characterized by respective nesting level numbers that increase with increasing separation of each respective nesting level from a reference level of the total input code; said processor receiving, from the user, a modification of at least one code block of the plurality of code blocks of the input code; said processor generating at least one modified code block respectively corresponding to the received modification; said processor generating a test case list of test cases from the input code by use of an impact analyzer comprised by the IDE, wherein each test case of the test case list comprises a respective test case identifier and a respective launching priority, wherein the respective launching priority quantifies how strongly each test case is associated with the at least one modified code block, wherein each test case is uniquely identified by the respective test case identifier, and wherein said generating the test case list comprises generating the test cases and determining the respective launching priority for each test case by (i) determining an association strength of each modified code block as measured by the nesting level in the hierarchy of each modified code block such that the association strength decreases as the nesting level increases for each modified code block and (ii) computing the launching priority as a sum of the association strengths of the modified code blocks; said processor producing a test run result for the at least one modified code block by asynchronously running the test cases of the test case list in a sequential order of increasing launching priority of the test cases; and said processor displaying the test run result to the user via a graphical user interface (GUI) of the computer system.