Modify the Hash#assert_valid_keys error message so that it shows the valid keys. Also, show the wrong value as it was entered.

{ :failore => "stuff", :funny => "business" }.assert_valid_keys([ :failure, :funny ])
=> ArgumentError: Unknown key: failore
{ 'failore' => "stuff", :funny => "business" }.assert_valid_keys([ :failure, :funny ])
=> ArgumentError: Unknown key: failore

{ 'failore' => "stuff", :funny => "business" }.assert_valid_keys([ :failure, :funny ])
=> ArgumentError: Unknown key: "failore". Valid keys are: :failure, :funny

{ :failore => "stuff", :funny => "business" }.assert_valid_keys([ :failure, :funny ])
=> ArgumentError: Unknown key: :failore. Valid keys are: :failure, :funny

Conflicts:
	activerecord/CHANGELOG.md

Closes #11624.

3 files changed, 9 insertions, 4 deletions

diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 18050969d0..e894ee5a3a 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,8 @@
+*   Show valid keys when `assert_valid_keys` raises an exception, and show the
+    wrong value as it was entered.
+
+    *Gonzalo Rodríguez-Baltanás Díaz*
+
 *   Both `cattr_*` and `mattr_*` method definitions now live in `active_support/core_ext/module/attribute_accessors`.
 
     Requires to `active_support/core_ext/class/attribute_accessors` are
diff --git a/activesupport/lib/active_support/core_ext/hash/keys.rb b/activesupport/lib/active_support/core_ext/hash/keys.rb
index f35c2be4c2..d31bbd5c88 100644
--- a/activesupport/lib/active_support/core_ext/hash/keys.rb
+++ b/activesupport/lib/active_support/core_ext/hash/keys.rb
@@ -61,13 +61,13 @@ class Hash
   # on a mismatch. Note that keys are NOT treated indifferently, meaning if you
   # use strings for keys but assert symbols as keys, this will fail.
   #
-  #   { name: 'Rob', years: '28' }.assert_valid_keys(:name, :age) # => raises "ArgumentError: Unknown key: years"
-  #   { name: 'Rob', age: '28' }.assert_valid_keys('name', 'age') # => raises "ArgumentError: Unknown key: name"
+  #   { name: 'Rob', years: '28' }.assert_valid_keys(:name, :age) # => raises "ArgumentError: Unknown key: :years. Valid keys are: :name, :age"
+  #   { name: 'Rob', age: '28' }.assert_valid_keys('name', 'age') # => raises "ArgumentError: Unknown key: :name. Valid keys are: 'name', 'age'"
   #   { name: 'Rob', age: '28' }.assert_valid_keys(:name, :age)   # => passes, raises nothing
   def assert_valid_keys(*valid_keys)
     valid_keys.flatten!
     each_key do |k|
-      raise ArgumentError.new("Unknown key: #{k}") unless valid_keys.include?(k)
+      raise ArgumentError.new("Unknown key: #{k.inspect}. Valid keys are: #{valid_keys.map(&:inspect).join(', ')}") unless valid_keys.include?(k)
     end
   end
 
diff --git a/activesupport/test/core_ext/hash_ext_test.rb b/activesupport/test/core_ext/hash_ext_test.rb
index b059bc3e89..f62efecc72 100644
--- a/activesupport/test/core_ext/hash_ext_test.rb
+++ b/activesupport/test/core_ext/hash_ext_test.rb
@@ -624,7 +624,7 @@ class HashExtTest < ActiveSupport::TestCase
       { :failure => "stuff", :funny => "business" }.assert_valid_keys(:failure, :funny)
     end
 
-    assert_raise(ArgumentError, "Unknown key: failore") do
+    assert_raise(ArgumentError, "Unknown key: :failore. Valid keys are: :failure, :funny") do
       { :failore => "stuff", :funny => "business" }.assert_valid_keys([ :failure, :funny ])
       { :failore => "stuff", :funny => "business" }.assert_valid_keys(:failure, :funny)
     end