Add exercise `find_factorial`'s subject and tests

rust/tests/find_factorial_test/Cargo.lock

@@ -0,0 +1,12 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "find_factorial"
+version = "0.1.0"
+
+[[package]]
+name = "find_factorial_test"
+version = "0.1.0"
+dependencies = [
+ "find_factorial",
+]

rust/tests/find_factorial_test/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "find_factorial_test"
+version = "0.1.0"
+authors = ["MSilva95 <miguel-silva98@hotmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+find_factorial = { path = "../../../../rust-piscine-solutions/find_factorial"}

rust/tests/find_factorial_test/src/main.rs

@@ -0,0 +1,34 @@
+// Complete this function to return the factorial of a given number
+
+pub fn factorial(num: u64) -> u64 {
+    match num {
+        0 | 1 => 1,
+        _ => factorial(num - 1) * num,
+    }
+}
+
+fn main() {
+    println!("The factorial of 0 = {}", factorial(0)); 
+    println!("The factorial of 1 = {}", factorial(1)); 
+    println!("The factorial of 5 = {}", factorial(5)); 
+    println!("The factorial of 10 = {}", factorial(10)); 
+    println!("The factorial of 19 = {}", factorial(19)); 
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn factorial_of_1() {
+        assert_eq!(1, factorial(0));
+        assert_eq!(1, factorial(1));
+        assert_eq!(120, factorial(5));
+        assert_eq!(40320, factorial(8));
+        assert_eq!(3628800, factorial(10));
+        assert_eq!(87178291200, factorial(14));
+        assert_eq!(6402373705728000, factorial(18));
+        assert_eq!(121645100408832000, factorial(19));
+        assert_eq!(2432902008176640000, factorial(20));
+    }
+}

subjects/find_factorial/README.md

@@ -0,0 +1,40 @@
+## find_factorial
+
+### Instruccions
+
+Complete the function `factorial` to return the factorial of a given number
+
+### Expected Function
+
+```rust
+pub fn factorial(num: u64) -> u64 {
+}
+```
+
+### Usage
+
+Here is a possible program to test your function :
+
+```rust
+use find_factorial::factorial;
+
+fn main() {
+    println!("The factorial of 0 = {}", factorial(0));
+    println!("The factorial of 1 = {}", factorial(1));
+    println!("The factorial of 5 = {}", factorial(5));
+    println!("The factorial of 10 = {}", factorial(10));
+    println!("The factorial of 19 = {}", factorial(19));
+}
+```
+
+And its output:
+
+```console
+student@ubuntu:~/[[ROOT]]/test$ cargo run
+The factorial of 0 = 1
+The factorial of 1 = 1
+The factorial of 5 = 120
+The factorial of 10 = 3628800
+The factorial of 19 = 121645100408832000
+student@ubuntu:~/[[ROOT]]/test$
+```