add tests

Cargo.lock

@@ -9,6 +9,7 @@ dependencies = [
  "anyhow",
  "env_logger",
  "log",
+ "pretty_assertions",
 ]
 
 [[package]]
@@ -81,6 +82,12 @@ version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5b63caa9aa9397e2d9480a9b13673856c78d8ac123288526c37d7839f2a86990"
 
+[[package]]
+name = "diff"
+version = "0.1.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "56254986775e3233ffa9c4d7d3faaf6d36a2c09d30b20687e9f88bc8bafc16c8"
+
 [[package]]
 name = "env_filter"
 version = "0.1.2"
@@ -128,6 +135,16 @@ version = "2.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
 
+[[package]]
+name = "pretty_assertions"
+version = "1.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3ae130e2f271fbc2ac3a40fb1d07180839cdbbe443c7a27e1e3c13c5cac0116d"
+dependencies = [
+ "diff",
+ "yansi",
+]
+
 [[package]]
 name = "regex"
 version = "1.11.1"
@@ -235,3 +252,9 @@ name = "windows_x86_64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
+
+[[package]]
+name = "yansi"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cfe53a6657fd280eaa890a3bc59152892ffa3e30101319d168b781ed6529b049"

Cargo.toml

@@ -7,3 +7,6 @@ edition = "2021"
 log = "0.4.22"
 env_logger = "0.11.5"
 anyhow = "1.0.93"
+
+[dev-dependencies]
+pretty_assertions = "1.4.1"

src/emulator.rs

@@ -6,31 +6,6 @@ use std::path::Path;
 
 const MEMORY_SIZE: usize = 4096;
 const NUMBER_OF_REGISTERS: usize = 16;
-
-/// Emulator emulates the Chip8 CPU.
-pub struct Emulator {
-    memory: [u8; MEMORY_SIZE],
-    registers: [u16; NUMBER_OF_REGISTERS],
-    program_counter: u16,
-}
-
-impl Emulator {
-    /// Creates a new `Emulator` instance.
-    ///
-    pub fn new() -> Emulator {
-        let mut emulator = Emulator {
-            memory: [0; 4096],
-            registers: [0; 16],
-            program_counter: 0,
-        };
-
-        emulator.load_font_data();
-
-        emulator
-    }
-
-    fn load_font_data(&mut self) {
-        info!("Loading font data...");
 const FONT_SPRITES: [u8; 80] = [
     0xF0, 0x90, 0x90, 0x90, 0xF0, // 0
     0x20, 0x60, 0x20, 0x20, 0x70, // 1
@@ -49,6 +24,47 @@ impl Emulator {
     0xF0, 0x80, 0xF0, 0x80, 0xF0, // E
     0xF0, 0x80, 0xF0, 0x80, 0x80, // F
 ];
+
+/// Emulator emulates the Chip8 CPU.
+pub struct Emulator {
+    /// Memory represents the emulator's memory.
+    memory: [u8; MEMORY_SIZE],
+    /// Registers holds the general purpose registers.
+    registers: [u8; NUMBER_OF_REGISTERS],
+    /// The index register store memory addresses.
+    index_register: u16,
+    /// The program counter register tracks the currently executing instruction.
+    program_counter: u16,
+    /// The delay timer register. It is decremented at a rate of 60 Hz until it reaches 0.
+    delay_timer: u8,
+    /// The sound timer register. It is decremented at a rate of 60 Hz until it reaches 0.
+    /// It plays a beeping sound when it's value is different from 0.
+    sound_timer: u8,
+    /// The stack pointer register.
+    stack_pointer: u8,
+}
+
+impl Emulator {
+    /// Creates a new `Emulator` instance.
+    ///
+    pub fn new() -> Emulator {
+        let mut emulator = Emulator {
+            memory: [0; 4096],
+            registers: [0; 16],
+            index_register: 0,
+            program_counter: 0,
+            delay_timer: 0,
+            sound_timer: 0,
+            stack_pointer: 0,
+        };
+
+        emulator.load_font_data();
+
+        emulator
+    }
+
+    fn load_font_data(&mut self) {
+        info!("Loading font data...");
         FONT_SPRITES
             .iter()
             .enumerate()
@@ -89,3 +105,33 @@ impl Emulator {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use pretty_assertions::assert_eq;
+
+    #[test]
+    fn test_load_font_data() {
+        let emulator = Emulator::new();
+        assert_eq!(emulator.memory[0xf0..0xf0 + 80], FONT_SPRITES)
+    }
+
+    #[test]
+    fn test_load_rom_ibm_logo() {
+        // Setup
+        let mut file = File::open("roms/ibm-logo.ch8").expect("Failed to test open ROM");
+        let mut rom_file_data: [u8; 132] = [0; 132];
+        file.read(&mut rom_file_data)
+            .expect("Failed to read test ROM");
+
+        // Test
+        let mut emulator = Emulator::new();
+        emulator
+            .load_rom("roms/ibm-logo.ch8")
+            .expect("failed to load ROM");
+
+        // Assert
+        assert_eq!(emulator.memory[0x200..0x200 + 132], rom_file_data)
+    }
+}