unit test part of ch11.3

ch11/test-organization/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "test-organization"
+version = "0.1.0"

ch11/test-organization/Cargo.toml

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+[package]
+name = "test-organization"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

ch11/test-organization/src/lib.rs

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+// Unit tests are small and more focused, testing one module in isolation
+// Integration tests are entirely external and use code in the same
+// way that any other external code would, using only the public
+// interface and potentially exercising mutliple modules per test
+//
+// For unit tests, convention is to create a module in each file
+// named tests for the test functions and annotate the module
+// with cfg(test). Integration tests don't get this
+//
+// For the integration tests section, go back to the adder folder
+// https://rust-book.cs.brown.edu/ch11-03-test-organization.html#integration-tests
+
+pub fn add(left: u64, right: u64) -> u64 {
+    left + right
+}
+
+// Can test internal functions
+fn internal_adder(left: usize, right: usize) -> usize {
+    left + right
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_works() {
+        let result = add(2, 2);
+        assert_eq!(result, 4);
+    }
+
+    #[test]
+    fn internal() {
+        let result = internal_adder(2, 2);
+        assert_eq!(result, 4);
+    }
+}