Make getting a user by the username case insensitive

What does this MR do?

This merge request makes sure that when creating a new user object searching by username, it does so in a case sensitive manor.

What are the relevant issue numbers?

Closes #38304 (closed)
Closes #27229 (closed)
Possibly solves #47601 (moved)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated (After searching, nothing in the docs suggest usernames are sensitive or insensitive),
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides

spec/finders/user_finder_spec.rb

@@ -5,10 +5,10 @@
 describe UserFinder do
   set(:user) { create(:user) }
 
-  describe '#execute' do
-    context 'when the user exists (id)' do
+  describe '#find_by_id' do
+    context 'when the user exists' do
       it 'returns the user' do
-        found = described_class.new(user.id).execute
+        found = described_class.new(user.id).find_by_id
 
         expect(found).to eq(user)
       end
@@ -16,57 +16,61 @@
 
     context 'when the user exists (id as string)' do
       it 'returns the user' do
-        found = described_class.new(user.id.to_s).execute
+        found = described_class.new(user.id.to_s).find_by_id
 
         expect(found).to eq(user)
       end
     end
 
-    context 'when the user exists (username)' do
-      it 'returns the user' do
-        found = described_class.new(user.username).execute
+    context 'when the user does not exist' do
+      it 'returns nil' do
+        found = described_class.new(1).find_by_id
 
-        expect(found).to eq(user)
+        expect(found).to be_nil
       end
     end
+  end
 
-    context 'when passing a non existing username to the id' do
-      it 'returns nil' do
-        found = described_class.new("non_existent_username").find_by_id
+  describe '#find_by_username' do
+    context 'when the user exists' do
+      it 'returns the user' do
+        found = described_class.new(user.username).find_by_username
 
-        expect(found).to be_nil
+        expect(found).to eq(user)
       end
     end
 
-    context 'when passing an existing username to the id' do
+    context 'when the user does not exist' do
       it 'returns nil' do
-        found = described_class.new(user.username).find_by_id
+        found = described_class.new("non_existent_username").find_by_username
 
         expect(found).to be_nil
       end
     end
+  end
 
-    context 'when passing a non existing id to the username' do
-      it 'returns nil' do
-        found = described_class.new(1).find_by_username
+  describe '#execute' do
+    context 'when the user exists (id)' do
+      it 'returns the user' do
+        found = described_class.new(user.id).execute
 
-        expect(found).to be_nil
+        expect(found).to eq(user)
       end
     end
 
-    context 'when passing an existing id to the username' do
-      it 'returns nil' do
-        found = described_class.new(user.id).find_by_username
+    context 'when the user exists (id as string)' do
+      it 'returns the user' do
+        found = described_class.new(user.id.to_s).execute
 
-        expect(found).to be_nil
+        expect(found).to eq(user)
       end
     end
 
-    context 'when passing an existing id (as string) to the username' do
-      it 'returns nil' do
-        found = described_class.new(user.id.to_s).find_by_username
+    context 'when the user exists (username)' do
+      it 'returns the user' do
+        found = described_class.new(user.username).execute
 
-        expect(found).to be_nil
+        expect(found).to eq(user)
       end
     end
 
@@ -87,10 +91,10 @@
     end
   end
 
-  describe '#execute!' do
-    context 'when the user exists (id)' do
+  describe '#find_by_id!' do
+    context 'when the user exists' do
       it 'returns the user' do
-        found = described_class.new(user.id).execute!
+        found = described_class.new(user.id).find_by_id!
 
         expect(found).to eq(user)
       end
@@ -98,57 +102,61 @@
 
     context 'when the user exists (id as string)' do
       it 'returns the user' do
-        found = described_class.new(user.id.to_s).execute!
+        found = described_class.new(user.id.to_s).find_by_id!
 
         expect(found).to eq(user)
       end
     end
 
-    context 'when the user exists (username)' do
-      it 'returns the user' do
-        found = described_class.new(user.username).execute!
+    context 'when the user does not exist' do
+      it 'raises ActiveRecord::RecordNotFound' do
+        finder = described_class.new(1)
 
-        expect(found).to eq(user)
+        expect { finder.find_by_id! }.to raise_error(ActiveRecord::RecordNotFound)
       end
     end
+  end
 
-    context 'when passing a non existing username to the id' do
-      it 'raises ActiveRecord::RecordNotFound' do
-        finder = described_class.new("non_existent_username")
+  describe '#find_by_username!' do
+    context 'when the user exists' do
+      it 'returns the user' do
+        found = described_class.new(user.username).find_by_username!
 
-        expect { finder.find_by_id! }.to raise_error(ActiveRecord::RecordNotFound)
+        expect(found).to eq(user)
       end
     end
 
-    context 'when passing an existing username to the id' do
+    context 'when the user does not exist' do
       it 'raises ActiveRecord::RecordNotFound' do
-        finder = described_class.new(user.username)
+        finder = described_class.new("non_existent_username")
 
-        expect { finder.find_by_id! }.to raise_error(ActiveRecord::RecordNotFound)
+        expect { finder.find_by_username! }.to raise_error(ActiveRecord::RecordNotFound)
       end
     end
+  end
 
-    context 'when passing a non existing id to the username' do
-      it 'raises ActiveRecord::RecordNotFound' do
-        finder = described_class.new(1)
+  describe '#execute!' do
+    context 'when the user exists (id)' do
+      it 'returns the user' do
+        found = described_class.new(user.id).execute!
 
-        expect { finder.find_by_username! }.to raise_error(ActiveRecord::RecordNotFound)
+        expect(found).to eq(user)
       end
     end
 
-    context 'when passing an existing id to the username' do
-      it 'raises ActiveRecord::RecordNotFound' do
-        finder = described_class.new(user.id)
+    context 'when the user exists (id as string)' do
+      it 'returns the user' do
+        found = described_class.new(user.id.to_s).execute!
 
-        expect { finder.find_by_username! }.to raise_error(ActiveRecord::RecordNotFound)
+        expect(found).to eq(user)
       end
     end
 
-    context 'when passing an existing id (as string) to the username' do
-      it 'raises ActiveRecord::RecordNotFound' do
-        finder = described_class.new(user.id.to_s)
+    context 'when the user exists (username)' do
+      it 'returns the user' do
+        found = described_class.new(user.username).execute!
 
-        expect { finder.find_by_username! }.to raise_error(ActiveRecord::RecordNotFound)
+        expect(found).to eq(user)
       end
     end