Add seed generator/populate w/tests

1 files changed, 111 insertions, 3 deletions

diff --git a/CLI/rust/src/game_of_life/generators/seed.rs b/CLI/rust/src/game_of_life/generators/seed.rs
index 41c8f5d..e3e3f12 100644
--- a/CLI/rust/src/game_of_life/generators/seed.rs
+++ b/CLI/rust/src/game_of_life/generators/seed.rs
@@ -1,6 +1,9 @@
 use crate::game_of_life::opts::Opts;
-use crate::game_of_life::simulation::universe::Universe;
+use crate::game_of_life::simulation::{plane::Plane, universe::Universe};
 use clap::Error;
+use rand::rngs::StdRng;
+use rand::{Rng, SeedableRng};
+use rand_distr::{Distribution, Uniform};
 
 #[cfg(test)]
 use mocktopus::macros::mockable;
@@ -10,6 +13,111 @@ use mocktopus::macros::mockable;
 /// The generation of the seed should be stable across different machines
 /// using the same language package, version, width and height.
 #[cfg_attr(test, mockable)]
-pub(crate) fn new(_opts: Opts) -> Result<Universe, Error> {
-    unimplemented!()
+pub(crate) fn new(opts: Opts) -> Result<Universe, Error> {
+    let range = generator(opts.seed);
+    Ok(populate(opts, range))
+}
+
+/// Create a StdRng using Uniform distribution for generating same data from
+/// the same seed
+fn generator(seed: usize) -> StdRng {
+    let mut range = StdRng::seed_from_u64(seed as u64);
+    Uniform::new_inclusive(0, 1).sample(&mut range);
+    range
+}
+
+#[cfg(test)]
+mod generator {
+    use super::*;
+
+    #[test]
+    fn seed_1337() {
+        let mut rng = generator(1337);
+        assert_eq!(rng.gen::<bool>(), true);
+        assert_eq!(rng.gen::<bool>(), false);
+        assert_eq!(rng.gen::<bool>(), true);
+        assert_eq!(rng.gen::<bool>(), true);
+        assert_eq!(rng.gen::<bool>(), false);
+    }
+
+    #[test]
+    fn seed_42() {
+        let mut rng = generator(42);
+        assert_eq!(rng.gen::<bool>(), true);
+        assert_eq!(rng.gen::<bool>(), false);
+        assert_eq!(rng.gen::<bool>(), true);
+        assert_eq!(rng.gen::<bool>(), true);
+        assert_eq!(rng.gen::<bool>(), true);
+    }
+}
+
+/// Return a universe struct with populated data from the seedable range
+fn populate(opts: Opts, mut range: StdRng) -> Universe {
+    let (width, height) = (opts.width as usize, opts.height as usize);
+    let mut current = Plane(vec![Plane(vec![false; width]); height]);
+    for i in 0..height {
+        for j in 0..width {
+            current[i as isize][j as isize] = range.gen()
+        }
+    }
+    Universe {
+        opts,
+        current,
+        future: Plane(vec![Plane(vec![false; width]); height]),
+    }
+}
+
+#[cfg(test)]
+mod populate {
+    use super::*;
+
+    fn opts(seed: usize) -> Opts {
+        Opts {
+            seed,
+            input: None,
+            width: 5,
+            height: 3,
+            live_cell: 'L',
+            dead_cell: 'D',
+            delay: 13,
+        }
+    }
+
+    #[test]
+    fn seed_1337() {
+        let rng = generator(1337);
+        let opts = opts(1337);
+        let universe = populate(opts.clone(), rng);
+        assert_eq!(
+            universe,
+            Universe {
+                opts,
+                future: Plane(vec![Plane(vec![false; 5]); 3]),
+                current: Plane(vec![
+                    Plane(vec![true, false, true, true, false]),
+                    Plane(vec![true, false, true, false, true]),
+                    Plane(vec![false, false, true, true, true]),
+                ]),
+            }
+        )
+    }
+
+    #[test]
+    fn seed_42() {
+        let rng = generator(42);
+        let opts = opts(42);
+        let universe = populate(opts.clone(), rng);
+        assert_eq!(
+            universe,
+            Universe {
+                opts,
+                future: Plane(vec![Plane(vec![false; 5]); 3]),
+                current: Plane(vec![
+                    Plane(vec![true, false, true, true, true]),
+                    Plane(vec![true, false, true, false, true]),
+                    Plane(vec![false, false, true, false, true]),
+                ]),
+            }
+        )
+    }
 }