feat: various fixes

clippy: rm unnecessary borrows
structure: move struct definitions around
tests: add unit test for matrix operations
errors: add custom error types

src/tests/matrix_test.rs

@@ -0,0 +1,54 @@
+use std::{error::Error, str::FromStr};
+
+use crate::types::{matrix::Matrix, matrix_err::ParseMatrixError};
+
+#[test]
+pub fn test_matrix_init_from_string() -> Result<(), ParseMatrixError> {
+    let data_target = vec![vec![1, 2, 3], vec![4, 5, 6], vec![7, 8, 9]];
+    let target = Matrix {
+        nrows: 3,
+        ncols: 3,
+        data: data_target,
+    };
+    let test = Matrix::from_str("1,2,3\n4,5,6\n7,8,9")?;
+    assert_eq!(target, test);
+    Ok(())
+}
+#[test]
+pub fn test_matrix_add() -> Result<(), ParseMatrixError> {
+    let m1 = Matrix::from_str("1,2,3\n4,5,6\n7,8,9")?;
+    let m2 = Matrix::from_str("1,1,1\n1,1,1\n1,1,1")?;
+    let t = Matrix::from_str("2,3,4\n5,6,7\n8,9,10")?;
+    assert_eq!(&m1 + &m2, t);
+    Ok(())
+}
+#[test]
+pub fn test_matrix_determinate() -> Result<(), ParseMatrixError> {
+    let m = Matrix::from_str("3,4\n5,6")?;
+    let det = 3 * 6 - 4 * 5;
+    assert_eq!(m.determinant(), det);
+    Ok(())
+}
+#[test]
+pub fn test_matrix_transposition() -> Result<(), ParseMatrixError> {
+    let m = Matrix::from_str("1,2,3\n4,5,6\n7,8,9")?;
+    let t = Matrix::from_str("1,4,7\n2,5,8\n3,6,9")?;
+    assert_eq!(m.transpose(), t);
+    Ok(())
+}
+#[test]
+pub fn test_matrix_parse_malformed() -> () {
+    let malformed = "1,23,\n,567,\n\n5";
+    let m = Matrix::from_str(malformed);
+    match m {
+        Ok(_) => panic!("This malformed matrix string should not have succeeded"),
+        Err(_) => (),
+    }
+}
+#[test]
+#[should_panic]
+pub fn test_matrix_add_bad_dimensions() -> () {
+    let bad = Matrix::from_str("1,1,1\n1,1,1").unwrap();
+    let add = Matrix::from_str("1,1\n1,1").unwrap();
+    let _ = &bad + &add;
+}