Use let to creat users in voter spec

We remove duplication, and we better isolate useless assignments.

spec/models/poll/voter_spec.rb

@@ -9,6 +9,7 @@ describe Poll::Voter do
   let(:officer_assignment) { create(:poll_officer_assignment) }
 
   describe "validations" do
+    let(:user) { create(:user, :level_two) }
 
     it "is valid" do
       expect(voter).to be_valid
@@ -31,8 +32,6 @@ describe Poll::Voter do
     end
 
     it "is not valid if the user has already voted in the same poll or booth_assignment" do
-      user = create(:user, :level_two)
-
       voter1 = create(:poll_voter, user: user, poll: poll)
       voter2 = build(:poll_voter, user: user, poll: poll)
 
@@ -41,8 +40,6 @@ describe Poll::Voter do
     end
 
     it "is not valid if the user has already voted in the same poll/booth" do
-      user = create(:user, :level_two)
-
       voter1 = create(:poll_voter, user: user, poll: poll, booth_assignment: booth_assignment)
       voter2 = build(:poll_voter, user: user, poll: poll, booth_assignment: booth_assignment)
 
@@ -51,8 +48,6 @@ describe Poll::Voter do
     end
 
     it "is not valid if the user has already voted in different booth in the same poll" do
-      user = create(:user, :level_two)
-
       create(:poll_voter, :from_booth, user: user, poll: poll, booth: create(:poll_booth))
 
       voter = build(:poll_voter, :from_booth, user: user, poll: poll, booth: booth)
@@ -62,8 +57,6 @@ describe Poll::Voter do
     end
 
     it "is valid if the user has already voted in the same booth in different poll" do
-      user = create(:user, :level_two)
-
       create(:poll_voter, :from_booth, user: user, booth: booth, poll: create(:poll))
 
       voter = build(:poll_voter, :from_booth, user: user, booth: booth, poll: poll)