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game/spec/ship_spec.rb

@@ -0,0 +1,95 @@
+# Nathan Hinton 2 Oct 2025
+
+# Test file for the ship object
+
+require './ship'
+
+RSpec.describe Ship do
+  let(:initial_x) { 0 }
+  let(:initial_y) { 0 }
+  subject(:ship) { Ship.new(initial_x, initial_y) }
+
+  describe '#initialize' do
+    it 'stores the given position' do
+      expect(ship.instance_variable_get(:@position)).to eq([initial_x, initial_y])
+    end
+
+    it 'sets the speed to 0.1' do
+      expect(ship.instance_variable_get(:@speed)).to eq(0.1)
+    end
+
+    it 'does not set @moving until a direction is chosen' do
+      expect(ship.instance_variable_get(:@moving)).to be_nil
+    end
+  end
+
+  describe '#tick' do
+    it 'does nothing (but does not raise an exception)' do
+      expect { ship.tick }.not_to raise_error
+    end
+  end
+
+  describe '#move' do
+    context 'when coordinates are valid' do
+      it 'accepts adjacent moves whose sum is even' do
+        # adjacent positions that satisfy the rules
+        expect { ship.move(1, 1) }.not_to raise_error   # sum = 2
+        expect { ship.move(2, 0) }.not_to raise_error   # sum = 2
+        expect { ship.move(0, 2) }.not_to raise_error   # sum = 2
+        expect { ship.move(-1, -1) }.not_to raise_error # sum = -2
+      end
+    end
+
+    context 'when the x + y sum is odd' do
+      it 'raises an ArgumentError' do
+        expect { ship.move(0, 1) }.to raise_error(
+          ArgumentError,
+          /must add to be even/
+        )
+      end
+    end
+
+    context 'when the target is not adjacent' do
+      it 'raises an ArgumentError' do
+        # distance > 1: difference of sums != 2
+        expect { ship.move(3, 3) }.to raise_error(
+          ArgumentError,
+          /must be to an adjcent space/
+        )
+        expect { ship.move(0, 0) }.to raise_error(
+          ArgumentError,
+          /must be to an adjcent space/
+        )
+      end
+    end
+  end
+
+  describe '#move_direction' do
+    it 'accepts direction values between 0 and 5' do
+      (0..5).each do |direction|
+        expect { ship.move_direction(direction) }.not_to raise_error
+        # verify the @moving vector matches the spec
+        expected = case direction
+                   when 0 then [2, 0]
+                   when 1 then [1, 1]
+                   when 2 then [-1, 1]
+                   when 3 then [-2, 0]
+                   when 4 then [-1, -1]
+                   when 5 then [1, -1]
+                   end
+        expect(ship.instance_variable_get(:@moving)).to eq(expected)
+      end
+    end
+
+    it 'raises an ArgumentError for invalid directions' do
+      expect { ship.move_direction(-1) }.to raise_error(
+        ArgumentError,
+        /must be between \(0..5\)/
+      )
+      expect { ship.move_direction(6) }.to raise_error(
+        ArgumentError,
+        /must be between \(0..5\)/
+      )
+    end
+  end
+end