Refactored memory space to remove big method (#3)

Co-authored-by: Saf <saf@irkenkitties.com>

lib/n65/memory_space.rb

@@ -92,21 +92,29 @@ module N65
     def normalize_address(address)
       case @type
       when :prog
-        return (address - 0x8000) if address_inside_prog_rom1?(address)
-        return (address - 0xC000) if address_inside_prog_rom2?(address)
-
-        raise(AccessOutsideProgRom, format('Address $%.4X is outside PROG ROM', address))
+        normalize_prog_rom_address(address)
       when :char
-        unless address_inside_char_rom?(address)
-          raise(AccessOutsideCharRom, format('Address $%.4X is outside CHAR ROM', address))
-        end
-
-        address
+        normalize_char_rom_address(address)
       else
         address
       end
     end
 
+    def normalize_prog_rom_address(address)
+      return (address - 0x8000) if address_inside_prog_rom1?(address)
+      return (address - 0xC000) if address_inside_prog_rom2?(address)
+
+      message = 'Address $%.4X is outside PROG ROM'
+      raise(AccessOutsideProgRom, format(message, address))
+    end
+
+    def normalize_char_rom_address(address)
+      return address if address_inside_char_rom?(address)
+
+      message = 'Address $%.4X is outside CHAR ROM'
+      raise(AccessOutsideCharRom, format(message, address))
+    end
+
     def address_inside_prog_rom1?(address)
       address >= 0x8000 && address < 0xC000
     end

spec/lib/n65/memory_space_spec.rb

@@ -47,7 +47,7 @@ RSpec.describe(N65::MemorySpace) do
     end
   end
 
-  describe '#read' do
+  describe '#read prog rom' do
     let(:address) { 0xC100 }
     let(:mirroed_address) { 0x8100 }
     let(:bank) { described_class.create_prog_rom }
@@ -76,7 +76,27 @@ RSpec.describe(N65::MemorySpace) do
     end
   end
 
-  describe '#write' do
+  describe '#read char rom' do
+    let(:address) { 0x100 }
+    let(:bank) { described_class.create_char_rom }
+    let(:data) { 'hi there'.bytes }
+
+    before { bank.write(address, data) }
+
+    context 'when reading from the bank' do
+      it 'can read from the bank' do
+        expect(bank.read(address, data.size)).to eq(data)
+      end
+    end
+
+    context 'when attempting to read out of bounds' do
+      it 'throws an error' do
+        expect { bank.read(0x2000, 0x10) }.to raise_error(described_class::AccessOutsideCharRom)
+      end
+    end
+  end
+
+  describe '#write prog rom' do
     let(:address) { 0xC100 }
     let(:mirroed_address) { 0x8100 }
     let(:bank) { described_class.create_prog_rom }
@@ -104,4 +124,24 @@ RSpec.describe(N65::MemorySpace) do
       end
     end
   end
+
+  describe '#write char rom' do
+    let(:address) { 0x100 }
+    let(:bank) { described_class.create_char_rom }
+    let(:data) { 'hi there'.bytes }
+
+    before { bank.write(address, data) }
+
+    context 'when reading from the bank' do
+      it 'can read from the bank' do
+        expect(bank.read(address, data.size)).to eq(data)
+      end
+    end
+
+    context 'when attempting to write out of bounds' do
+      it 'throws an error' do
+        expect { bank.write(0x2000, data) }.to raise_error(described_class::AccessOutsideCharRom)
+      end
+    end
+  end
 end