Modify initial distribution of tables to guarantee there is no single-person table

app/services/tables/distribution.rb

@@ -13,9 +13,10 @@ module Tables
     end
 
     def random_distribution(people)
-      @tables = []
-
-      @tables << Table.new(people.slice!(0..rand(@min_per_table..@max_per_table))) while people.any?
+      min_tables = (people.count * 1.0 / @max_per_table).ceil
+      max_tables = (people.count * 1.0 / @min_per_table).ceil
+      @tables = people.in_groups(rand(min_tables..max_tables), false)
+                      .map { |group| Table.new(group) }
     end
 
     def discomfort

spec/services/tables/distribution_spec.rb

@@ -0,0 +1,23 @@
+require 'rails_helper'
+
+module Tables
+  RSpec.describe Distribution do
+    describe '#random_distribution' do
+      let(:subject) { described_class.new(min_per_table: 5, max_per_table: 10) }
+
+      context 'when there are fewer people than the minimum per table' do
+        it 'creates one table' do
+          subject.random_distribution([1, 2, 3, 4])
+          expect(subject.tables.count).to eq(1)
+        end
+      end
+
+      context 'when there are more people than the maximum per table' do
+        it 'creates multiple tables' do
+          subject.random_distribution([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11])
+          expect(subject.tables.count).to be > 1
+        end
+      end
+    end
+  end
+end