scraper.rs

extern crate reqwest;
use std::time::SystemTime;
use std::fs::File;
use std::io::prelude::*;

fn write_file(filename: &str, data: &str) {
    let bytes = data.as_bytes();
    let mut file = File::create(filename).expect("Error creating file");
    file.write_all(bytes).expect("Error writing file");
}

fn read_file(filename: &str) -> String {
    let mut file = File::open(filename).expect("Error opening file");
    let mut contents = String::new();
    file.read_to_string(&mut contents);
    return contents;
}

fn gen_timestamp() -> String {
    match SystemTime::now().duration_since(SystemTime::UNIX_EPOCH) {
        Ok(n) => n.as_secs().to_string(),
        Err(_) => panic!("SystemTime before UNIX EPOCH!"),
    }
}

fn scrape(url: &str, term: &str) -> String {
    
    // Make the http request for the resource
    // and assign the text response to a variable
    let response_text = reqwest::get(url)
        .expect("Unable to find url")
        .text()
        .expect("Unable to read response");

    // Create a unique token for filename
    let timestamp = gen_timestamp();
    let filename = ["scape", &timestamp, ".html"].join("");

    // Write the response text to disk
    write_file(&filename, &response_text);

    // Read the file to a variable
    let scrape_data = read_file(&filename);

    // Check if the search term is present
    if scrape_data.contains(term) {
        
        // Return a message to the user that the search term was found
        return ["Found", term, "in", url].join(" ");
    }

    // Return a message to the user that the search term was not found
    return [term, "was not found in", url].join(" ");
}

fn main() {
    println!("{}", scrape("URL", "SEARCH_TERM"));
}

Some small idiomatic improvements:
Line 20: The match arms are doing the same thing as expect.
Line 37, 49 and 53: Use format! from std::format.