> If a code change is outside of the code coverage of the test, it doesn't affect the test.

This assertion questionable, the extent it is true it is language specific.

Here is a counterexample in Java:

  // foo.java 
  public class Foo {
    public static final int LENGTH = 10;
  }

  // bar.java 
  public class Bar {
    public int getFooLength() {
      return Foo.LENGTH;
    }
  }

Code coverage tools will not highlight Foo as being touched when Bar.getFooLength is invoked, even though a test asserting that getFooLength() is 10 will fail or succeed depending on Foo.LENGTH. The reason for this is that Foo.LENGTH is inlined in Bar. If you for example wanted to patch a new version of the value, you need to supply Bar.class to affect the change; patching Foo alone would do nothing.

C and C++ likewise do not satisfy this requirement because macros.