Fix csv export coverage in export spec (mastodon#1691)

spec/models/export_spec.rb

@@ -2,12 +2,32 @@
 
 describe Export do
   describe 'to_csv' do
-    it 'returns a csv of the accounts' do
+    before do
       one = Account.new(username: 'one', domain: 'local.host')
       two = Account.new(username: 'two', domain: 'local.host')
       accounts = [one, two]
 
-      export = Export.new(accounts).to_csv
+      @account = double(blocking: accounts, muting: accounts, following: accounts)
+    end
+
+    it 'returns a csv of the blocked accounts' do
+      export = Export.new(@account).to_blocked_accounts_csv
+      results = export.strip.split
+
+      expect(results.size).to eq 2
+      expect(results.first).to eq 'one@local.host'
+    end
+
+    it 'returns a csv of the muted accounts' do
+      export = Export.new(@account).to_muted_accounts_csv
+      results = export.strip.split
+
+      expect(results.size).to eq 2
+      expect(results.first).to eq 'one@local.host'
+    end
+
+    it 'returns a csv of the following accounts' do
+      export = Export.new(@account).to_following_accounts_csv
       results = export.strip.split
 
       expect(results.size).to eq 2