From 91820b4a7343719977eec4caefed197812dfa584 Mon Sep 17 00:00:00 2001
From: laentropia <aadrian887mh@gmail.com>
Date: Wed, 29 Apr 2026 17:31:43 -0600
Subject: [PATCH] test: tests for sub

---
 src/lib.rs | 160 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 158 insertions(+), 2 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 362a29e..4288d87 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -474,7 +474,7 @@ impl Add for Matrix {
             return Err(MatrixError::InvalidSizeForAdd);
         }
 
-        let mut new_data = Vec::new();
+        let mut new_data = Vec::with_capacity(self.data.len());
         for i in 0..self.data.len() {
             new_data.push(self.data[i] + other.data[i]);
         }
@@ -495,7 +495,7 @@ impl Sub for Matrix {
             return Err(MatrixError::InvalidSizeForSub);
         }
 
-        let mut new_data = Vec::new();
+        let mut new_data = Vec::with_capacity(self.data.len());
         for i in 0..self.data.len() {
             new_data.push(self.data[i] - other.data[i]);
         }
@@ -3241,4 +3241,160 @@ mod tests {
 
         assert_eq!(result.data, expected);
     }
+
+    #[test]
+    fn test_sub_basic() {
+        let a = Matrix {
+            rows: 2,
+            columns: 2,
+            data: vec![
+                Fraction::from(5),
+                Fraction::from(6),
+                Fraction::from(7),
+                Fraction::from(8),
+            ],
+        };
+
+        let b = Matrix {
+            rows: 2,
+            columns: 2,
+            data: vec![
+                Fraction::from(1),
+                Fraction::from(2),
+                Fraction::from(3),
+                Fraction::from(4),
+            ],
+        };
+
+        let result = (a - b).unwrap();
+
+        let expected = vec![
+            Fraction::from(4),
+            Fraction::from(4),
+            Fraction::from(4),
+            Fraction::from(4),
+        ];
+
+        assert_eq!(result.data, expected);
+    }
+
+    #[test]
+    fn test_sub_zero_matrix() {
+        let a = Matrix {
+            rows: 2,
+            columns: 2,
+            data: vec![
+                Fraction::from(1),
+                Fraction::from(2),
+                Fraction::from(3),
+                Fraction::from(4),
+            ],
+        };
+
+        let zero = Matrix::new(2, 2, Fraction::from(0)).unwrap();
+
+        let result = (a.clone() - zero).unwrap();
+
+        assert_eq!(result.data, a.data);
+    }
+
+    #[test]
+    fn test_sub_self() {
+        let a = Matrix::new(3, 3, Fraction::from(5)).unwrap();
+
+        let result = (a.clone() - a).unwrap();
+
+        assert!(result.data.iter().all(|x| x.is_zero()));
+    }
+
+    #[test]
+    fn test_sub_negative_values() {
+        let a = Matrix {
+            rows: 2,
+            columns: 2,
+            data: vec![
+                Fraction::from(1),
+                Fraction::from(-2),
+                Fraction::from(3),
+                Fraction::from(-4),
+            ],
+        };
+
+        let b = Matrix {
+            rows: 2,
+            columns: 2,
+            data: vec![
+                Fraction::from(-1),
+                Fraction::from(2),
+                Fraction::from(-3),
+                Fraction::from(4),
+            ],
+        };
+
+        let result = (a - b).unwrap();
+
+        let expected = vec![
+            Fraction::from(2),
+            Fraction::from(-4),
+            Fraction::from(6),
+            Fraction::from(-8),
+        ];
+
+        assert_eq!(result.data, expected);
+    }
+
+    #[test]
+    fn test_sub_invalid_size() {
+        let a = Matrix::new(2, 2, Fraction::from(1)).unwrap();
+        let b = Matrix::new(3, 2, Fraction::from(1)).unwrap();
+
+        let result = a - b;
+
+        assert!(matches!(result, Err(MatrixError::InvalidSizeForSub)));
+    }
+
+    #[test]
+    fn test_sub_not_commutative() {
+        let a = Matrix::new(2, 2, Fraction::from(3)).unwrap();
+        let b = Matrix::new(2, 2, Fraction::from(1)).unwrap();
+
+        let res1 = (a.clone() - b.clone()).unwrap();
+        let res2 = (b - a).unwrap();
+
+        assert_ne!(res1.data, res2.data);
+    }
+
+    #[test]
+    fn test_sub_anti_symmetry() {
+        let a = Matrix::new(2, 2, Fraction::from(3)).unwrap();
+        let b = Matrix::new(2, 2, Fraction::from(1)).unwrap();
+
+        let res1 = (a.clone() - b.clone()).unwrap();
+        let res2 = (b - a).unwrap();
+
+        for i in 0..res1.data.len() {
+            assert_eq!(res1.data[i], -res2.data[i]);
+        }
+    }
+
+    #[test]
+    fn test_sub_fractions() {
+        let a = Matrix {
+            rows: 1,
+            columns: 2,
+            data: vec![Fraction::new(3, 4).unwrap(), Fraction::new(5, 6).unwrap()],
+        };
+
+        let b = Matrix {
+            rows: 1,
+            columns: 2,
+            data: vec![Fraction::new(1, 4).unwrap(), Fraction::new(1, 6).unwrap()],
+        };
+
+        let result = (a - b).unwrap();
+
+        let expected = vec![Fraction::new(1, 2).unwrap(), Fraction::new(2, 3).unwrap()];
+
+        assert_eq!(result.data, expected);
+    }
 }