Add SRM test example

examples/srm-test/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "srm-test"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+rand = "0.8.5"
+
+[dependencies.optimizely]
+path = "../../optimizely"
+features = ["online"]
+
+[dependencies.uuid]
+version = "1.3.0"
+features = ["v4", "fast-rng"]

examples/srm-test/src/main.rs

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+use optimizely::{decision::DecideOptions, Client};
+use std::{collections::HashMap, error::Error, ops::AddAssign};
+use uuid::Uuid;
+
+const FILE_PATH: &str = "../../datafiles/sandbox.json";
+const FLAG_KEY: &str = "buy_button";
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let client = Client::from_local_datafile(FILE_PATH)?.initialize();
+
+    // Do not send any decision events during SRM testing
+    let decide_options = DecideOptions {
+        disable_decision_event: true,
+        ..DecideOptions::default()
+    };
+
+    // Create counter
+    let mut counter: HashMap<String, usize> = HashMap::new();
+
+    // Run a two million times
+    for _ in 0..2_000_000 {
+        // Generate visitor ID using UUIDv4
+        let user_id = Uuid::new_v4().as_hyphenated().to_string();
+
+        // Get variation key
+        let variation_key = client.create_user_context(&user_id)
+            .decide_with_options(FLAG_KEY, &decide_options)
+            .variation_key()
+            .to_string();
+
+        // Count variation
+        counter.entry(variation_key).or_insert(0).add_assign(1);
+    }
+
+    // Dump counter to stdout
+    for (key, total) in counter {
+        println!("Variation '{}' had {} visitors", key, total);
+    }
+
+    Ok(())
+}