Add subject and test for the exercise `name_initials`

rust/tests/name_initials_test/Cargo.lock

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+# It is not intended for manual editing.
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+dependencies = [
+ "jemalloc-sys",
+ "libc",
+ "paste",
+]
+
+[[package]]
+name = "jemalloc-sys"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
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+ "fs_extra",
+ "libc",
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+ "libc",
+]
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+checksum = "4d58d1b70b004888f764dfbf6a26a3b0342a1632d33968e4a179d8011c760614"
+
+[[package]]
+name = "name_initials"
+version = "0.1.0"
+dependencies = [
+ "jemalloc-ctl",
+ "jemallocator",
+]
+
+[[package]]
+name = "name_initials_test"
+version = "0.1.0"
+dependencies = [
+ "jemalloc-ctl",
+ "jemallocator",
+ "name_initials",
+]
+
+[[package]]
+name = "paste"
+version = "0.1.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "45ca20c77d80be666aef2b45486da86238fabe33e38306bd3118fe4af33fa880"
+dependencies = [
+ "paste-impl",
+ "proc-macro-hack",
+]
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+[[package]]
+name = "paste-impl"
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+dependencies = [
+ "proc-macro-hack",
+]
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+[[package]]
+name = "proc-macro-hack"
+version = "0.5.19"
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+checksum = "dbf0c48bc1d91375ae5c3cd81e3722dff1abcf81a30960240640d223f59fe0e5"

rust/tests/name_initials_test/Cargo.toml

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+[package]
+name = "name_initials_test"
+version = "0.1.0"
+authors = ["lee <lee-dasilva@hotmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+jemalloc-ctl = "0.3.3"
+jemallocator = "0.3.2"
+name_initials = { path = "../../../../rust-piscine-solutions/name_initials"}

rust/tests/name_initials_test/src/main.rs

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+/*
+## name_initials
+
+### Instructions
+
+Create a function called `initials`, this function will receive a vector of string literals
+with names and return a vector of Strings with the initials of each name.
+
+### Example:
+
+```rust
+```
+
+> This exercise will test the **heap allocation** of your function!
+> So try your best to allocate the minimum data on the heap!
+
+### Notions
+
+- https://doc.rust-lang.org/1.22.0/book/first-edition/the-stack-and-the-heap.html
+
+*/
+
+#[global_allocator]
+static ALLOC: jemallocator::Jemalloc = jemallocator::Jemalloc;
+
+#[allow(unused_imports)]
+use name_initials::*;
+
+#[allow(dead_code)]
+fn main() {
+	let mut names = vec!["Harry Potter", "Someone Else", "J. L.", "Barack Obama"];
+	println!("{:?}", initials(&mut names));
+	// output: ["H. P.", "S. E.", "J. L.", "B. O."]
+}
+
+#[allow(unused_imports)]
+use jemalloc_ctl::{epoch, stats};
+
+#[allow(dead_code)]
+struct Test<'a> {
+	names: Vec<&'a str>,
+	result: Vec<&'a str>,
+}
+
+// solution that will run against the students solution
+// this function uses the less heap allocation
+#[allow(dead_code)]
+fn initials_sol(arr: &mut Vec<&str>) -> Vec<String> {
+	arr.iter()
+		.map(|ele| {
+			let mut names = ele.split_whitespace();
+			let mut a = names.next().unwrap().chars().nth(0).unwrap().to_string();
+			a.push_str(". ");
+			let mut b = names.next().unwrap().chars().nth(0).unwrap().to_string();
+			b.push_str(".");
+			a.push_str(&b);
+			a
+		})
+		.collect()
+}
+
+#[test]
+fn test_memory_allocation() {
+	// the statistics tracked by jemalloc are cached
+	// The epoch controls when they are refreshed
+	let e = epoch::mib().unwrap();
+	// allocated: number of bytes allocated by the application
+	let allocated = stats::allocated::mib().unwrap();
+	let mut test_value = vec![
+		"Lee Silva",
+		"Harry Potter",
+		"Someone Else",
+		"J. L.",
+		"Barack Obama",
+	];
+
+	initials_sol(&mut test_value);
+	// this will advance with the epoch giving the its old value
+	// where we read the updated heap allocation using the `allocated.read()`
+	e.advance().unwrap();
+	let solution = allocated.read().unwrap();
+
+	initials(&mut test_value);
+	e.advance().unwrap();
+	let student = allocated.read().unwrap();
+
+	assert!(
+		student <= solution,
+		format!(
+			"your heap allocation is {}, and it must be less or equal to {}",
+			student, solution
+		)
+	);
+}
+
+#[test]
+fn test_function() {
+	let cases = vec![
+		Test {
+			names: vec!["Harry Potter", "Someone Else", "J. L.", "Barack Obama"],
+			result: vec!["H. P.", "S. E.", "J. L.", "B. O."],
+		},
+		Test {
+			names: vec![
+				"James John",
+				"David Joseph",
+				"Matthew Brian",
+				"Jacob Sousa",
+				"Bruce Banner",
+				"Scarlett Johansson",
+				"Graydon Hoare",
+			],
+			result: vec![
+				"J. J.", "D. J.", "M. B.", "J. S.", "B. B.", "S. J.", "G. H.",
+			],
+		},
+	];
+
+	for mut v in cases {
+		assert_eq!(
+			initials(&mut v.names),
+			v.result
+				.iter()
+				.map(|ele| ele.to_string())
+				.collect::<Vec<String>>()
+		);
+	}
+}

subjects/name_initials/README.md

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+## name_initials
+
+### Instructions
+
+Create a function called `initials`, this function will receive a vector of string literals
+with names and return a vector of Strings with the initials of each name.
+
+> This exercise will test the **heap allocation** of your function!
+> So try your best to allocate the minimum data on the heap!
+
+### Notions
+
+- https://doc.rust-lang.org/1.22.0/book/first-edition/the-stack-and-the-heap.html
+
+### Expected Function
+
+```rust
+fn initials(names: &mut Vec<&str>) -> Vec<String> {
+}
+```
+
+### Usage
+
+Here is a program to test your function
+
+```rust
+use name_initials::initials;
+
+fn main() {
+    let names = vec!["Harry Potter", "Someone Else", "J. L.", "Barack Obama"]
+    println!("{:?}", initials(names));
+}
+```
+
+And its output
+
+```console
+student@ubuntu:~/[[ROOT]]/test$ cargo run
+["H. P.", "S. E.", "J. L.", "B. O."]
+student@ubuntu:~/[[ROOT]]/test$
+```