`assert_changes` should always assert some change

While using `assert_changes`, I came across some unexpected behavior:
if you provide a `to:` argument, and the expression matches but didn't
actually change, the assertion will pass.

The way `assert_changes` reads, I assumed that it would both assert
that there was any change at all, _and_ that the expression changed to
match my `to:` argument.

In the case of just a `from:` argument, `assert_changes` does what I
expect as well. It asserts that the before value `=== from` and that
the after value changed.

My key change is that `assert_changes` will now _always_ assert that
expression changes, no matter what combination of `from:` and `to:`
arguments

1 files changed, 5 insertions, 0 deletions

diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 889919855c..a4c90c8b44 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,8 @@
+*   `assert_changes` will always assert that the expression changes,
+    regardless of `from:` and `to:` argument combinations.
+
+    *Daniel Ma*
+
 *   Allow `Range#include?` on TWZ ranges
 
     In #11474 we prevented TWZ ranges being iterated over which matched