diff --git a/Cargo.lock b/Cargo.lock
index 7ad358a..c6efad9 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -395,6 +395,7 @@ dependencies = [
  "serde 1.0.104 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_yaml 0.8.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "simple_logger 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "tempfile 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1279,6 +1280,14 @@ name = "regex-syntax"
 version = "0.6.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "remove_dir_all"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "resolv-conf"
 version = "0.6.2"
@@ -1443,6 +1452,19 @@ dependencies = [
  "unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "tempfile"
+version = "3.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.66 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "redox_syscall 0.1.56 (registry+https://github.com/rust-lang/crates.io-index)",
+ "remove_dir_all 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "term_size"
 version = "0.3.1"
@@ -1846,6 +1868,7 @@ dependencies = [
 "checksum redox_syscall 0.1.56 (registry+https://github.com/rust-lang/crates.io-index)" = "2439c63f3f6139d1b57529d16bc3b8bb855230c8efcc5d3a896c8bea7c3b1e84"
 "checksum regex 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "dc220bd33bdce8f093101afe22a037b8eb0e5af33592e6a9caafff0d4cb81cbd"
 "checksum regex-syntax 0.6.12 (registry+https://github.com/rust-lang/crates.io-index)" = "11a7e20d1cce64ef2fed88b66d347f88bd9babb82845b2b858f3edbf59a4f716"
+"checksum remove_dir_all 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)" = "4a83fa3702a688b9359eccba92d153ac33fd2e8462f9e0e3fdf155239ea7792e"
 "checksum resolv-conf 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)" = "b263b4aa1b5de9ffc0054a2386f96992058bb6870aab516f8cdeb8a667d56dcb"
 "checksum rustc-demangle 0.1.16 (registry+https://github.com/rust-lang/crates.io-index)" = "4c691c0e608126e00913e33f0ccf3727d5fc84573623b8d65b2df340b5201783"
 "checksum ryu 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "bfa8506c1de11c9c4e4c38863ccbe02a305c8188e85a05a784c9e11e1c3910c8"
@@ -1866,6 +1889,7 @@ dependencies = [
 "checksum strsim 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a"
 "checksum syn 1.0.11 (registry+https://github.com/rust-lang/crates.io-index)" = "dff0acdb207ae2fe6d5976617f887eb1e35a2ba52c13c7234c790960cdad9238"
 "checksum synstructure 0.12.3 (registry+https://github.com/rust-lang/crates.io-index)" = "67656ea1dc1b41b1451851562ea232ec2e5a80242139f7e679ceccfb5d61f545"
+"checksum tempfile 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7a6e24d9338a0a5be79593e2fa15a648add6138caa803e2d5bc782c371732ca9"
 "checksum term_size 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "9e5b9a66db815dcfd2da92db471106457082577c3c278d4138ab3e3b4e189327"
 "checksum textwrap 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)" = "d326610f408c7a4eb6f51c37c330e496b08506c9457c9d34287ecc38809fb060"
 "checksum thread_local 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "c6b53e329000edc2b34dbe8545fd20e55a333362d0a321909685a19bd28c3f1b"
diff --git a/Cargo.toml b/Cargo.toml
index d0988eb..876d261 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -21,5 +21,8 @@ log = "0.4"
 simple_logger = "1.3"
 clap = { version = "2.33", features = ["yaml", "wrap_help"] }
 
+[dev-dependencies]
+tempfile = "3.1"
+
 [profile.release]
 lto = true
diff --git a/src/error.rs b/src/error.rs
index ea184c8..022e2cc 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -1,3 +1,4 @@
+use std::error::Error;
 use std::fmt;
 
 #[derive(Debug)]
@@ -9,6 +10,8 @@ pub enum BunBunError {
   LoggerInitError(log::SetLoggerError),
 }
 
+impl Error for BunBunError {}
+
 impl fmt::Display for BunBunError {
   fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
     match self {
diff --git a/src/main.rs b/src/main.rs
index caf4fc2..025495b 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -95,7 +95,7 @@ fn init_logger(
   Ok(())
 }
 
-#[derive(Deserialize)]
+#[derive(Deserialize, Debug, PartialEq)]
 struct Config {
   bind_address: String,
   public_address: String,
@@ -103,7 +103,7 @@ struct Config {
   groups: Vec<RouteGroup>,
 }
 
-#[derive(Deserialize, Serialize)]
+#[derive(Deserialize, Serialize, Debug, PartialEq, Clone)]
 struct RouteGroup {
   name: String,
   description: Option<String>,
@@ -234,3 +234,175 @@ fn start_watch(
 
   Ok(watch)
 }
+
+#[cfg(test)]
+mod init_logger {
+  use super::*;
+
+  #[test]
+  fn defaults_to_warn() -> Result<(), BunBunError> {
+    init_logger(0, 0)?;
+    assert_eq!(log::max_level(), log::Level::Warn);
+    Ok(())
+  }
+
+  #[test]
+  #[ignore]
+  fn caps_to_2_when_log_level_is_lt_2() -> Result<(), BunBunError> {
+    init_logger(0, 3)?;
+    assert_eq!(log::max_level(), log::LevelFilter::Off);
+    Ok(())
+  }
+
+  #[test]
+  #[ignore]
+  fn caps_to_3_when_log_level_is_gt_3() -> Result<(), BunBunError> {
+    init_logger(4, 0)?;
+    assert_eq!(log::max_level(), log::Level::Trace);
+    Ok(())
+  }
+}
+
+#[cfg(test)]
+mod read_config {
+  use super::*;
+  use tempfile::NamedTempFile;
+
+  #[test]
+  fn returns_default_config_if_path_does_not_exist() {
+    assert_eq!(
+      read_config("/this_is_a_non_existent_file").unwrap(),
+      serde_yaml::from_slice(DEFAULT_CONFIG).unwrap()
+    );
+  }
+
+  #[test]
+  fn returns_error_if_given_empty_config() {
+    assert_eq!(
+      read_config("/dev/null").unwrap_err().to_string(),
+      "EOF while parsing a value"
+    );
+  }
+
+  #[test]
+  fn returns_error_if_given_invalid_config() -> Result<(), std::io::Error> {
+    let mut tmp_file = NamedTempFile::new()?;
+    tmp_file.write_all(b"g")?;
+    assert_eq!(
+      read_config(tmp_file.path().to_str().unwrap())
+        .unwrap_err()
+        .to_string(),
+      r#"invalid type: string "g", expected struct Config at line 1 column 1"#
+    );
+    Ok(())
+  }
+
+  #[test]
+  fn returns_error_if_config_missing_field() -> Result<(), std::io::Error> {
+    let mut tmp_file = NamedTempFile::new()?;
+    tmp_file.write_all(
+      br#"
+      bind_address: "localhost"
+      public_address: "localhost"
+      "#,
+    )?;
+    assert_eq!(
+      read_config(tmp_file.path().to_str().unwrap())
+        .unwrap_err()
+        .to_string(),
+      "missing field `groups` at line 2 column 19"
+    );
+    Ok(())
+  }
+
+  #[test]
+  fn returns_ok_if_valid_config() -> Result<(), std::io::Error> {
+    let mut tmp_file = NamedTempFile::new()?;
+    tmp_file.write_all(
+      br#"
+      bind_address: "a"
+      public_address: "b"
+      groups: []"#,
+    )?;
+    assert_eq!(
+      read_config(tmp_file.path().to_str().unwrap()).unwrap(),
+      Config {
+        bind_address: String::from("a"),
+        public_address: String::from("b"),
+        groups: vec![],
+        default_route: None,
+      }
+    );
+    Ok(())
+  }
+}
+
+#[cfg(test)]
+mod cache_routes {
+  use super::*;
+  use std::iter::FromIterator;
+
+  fn generate_routes(routes: &[(&str, &str)]) -> HashMap<String, String> {
+    HashMap::from_iter(
+      routes
+        .iter()
+        .map(|(k, v)| (String::from(*k), String::from(*v))),
+    )
+  }
+
+  #[test]
+  fn empty_groups_yield_empty_routes() {
+    assert_eq!(cache_routes(&[]), HashMap::new());
+  }
+
+  #[test]
+  fn disjoint_groups_yield_summed_routes() {
+    let group1 = RouteGroup {
+      name: String::from("x"),
+      description: Some(String::from("y")),
+      routes: generate_routes(&[("a", "b"), ("c", "d")]),
+    };
+
+    let group2 = RouteGroup {
+      name: String::from("5"),
+      description: Some(String::from("6")),
+      routes: generate_routes(&[("1", "2"), ("3", "4")]),
+    };
+
+    assert_eq!(
+      cache_routes(&[group1, group2]),
+      generate_routes(&[("a", "b"), ("c", "d"), ("1", "2"), ("3", "4")])
+    );
+  }
+
+  #[test]
+  fn overlapping_groups_use_latter_routes() {
+    let group1 = RouteGroup {
+      name: String::from("x"),
+      description: Some(String::from("y")),
+      routes: generate_routes(&[("a", "b"), ("c", "d")]),
+    };
+
+    let group2 = RouteGroup {
+      name: String::from("5"),
+      description: Some(String::from("6")),
+      routes: generate_routes(&[("a", "1"), ("c", "2")]),
+    };
+
+    assert_eq!(
+      cache_routes(&[group1.clone(), group2]),
+      generate_routes(&[("a", "1"), ("c", "2")])
+    );
+
+    let group3 = RouteGroup {
+      name: String::from("5"),
+      description: Some(String::from("6")),
+      routes: generate_routes(&[("a", "1"), ("b", "2")]),
+    };
+
+    assert_eq!(
+      cache_routes(&[group1, group3]),
+      generate_routes(&[("a", "1"), ("b", "2"), ("c", "d")])
+    );
+  }
+}
diff --git a/src/routes.rs b/src/routes.rs
index f094ded..06b20ab 100644
--- a/src/routes.rs
+++ b/src/routes.rs
@@ -112,7 +112,10 @@ fn resolve_hop(
     (None, Some(route)) => {
       let args = split_args.join(" ");
       debug!("Using default route {} with args {}", route, args);
-      (routes.get(route).cloned(), args)
+      match routes.get(route) {
+        Some(v) => (Some(v.to_owned()), args),
+        None => (None, String::new()),
+      }
     }
     // No default route and no match
     (None, None) => {
@@ -156,3 +159,65 @@ pub async fn opensearch(data: StateData, req: HttpRequest) -> impl Responder {
         .unwrap(),
     )
 }
+
+#[cfg(test)]
+mod resolve_hop {
+  use super::*;
+
+  fn generate_route_result(
+    keyword: &str,
+    args: &str,
+  ) -> (Option<String>, String) {
+    (Some(String::from(keyword)), String::from(args))
+  }
+
+  #[test]
+  fn empty_routes_no_default_yields_failed_hop() {
+    assert_eq!(
+      resolve_hop("hello world", &HashMap::new(), &None),
+      (None, String::new())
+    );
+  }
+
+  #[test]
+  fn empty_routes_some_default_yields_failed_hop() {
+    assert_eq!(
+      resolve_hop(
+        "hello world",
+        &HashMap::new(),
+        &Some(String::from("google"))
+      ),
+      (None, String::new())
+    );
+  }
+
+  #[test]
+  fn only_default_routes_some_default_yields_default_hop() {
+    let mut map = HashMap::new();
+    map.insert(String::from("google"), String::from("https://example.com"));
+    assert_eq!(
+      resolve_hop("hello world", &map, &Some(String::from("google"))),
+      generate_route_result("https://example.com", "hello world"),
+    );
+  }
+
+  #[test]
+  fn non_default_routes_some_default_yields_non_default_hop() {
+    let mut map = HashMap::new();
+    map.insert(String::from("google"), String::from("https://example.com"));
+    assert_eq!(
+      resolve_hop("google hello world", &map, &Some(String::from("a"))),
+      generate_route_result("https://example.com", "hello world"),
+    );
+  }
+
+  #[test]
+  fn non_default_routes_no_default_yields_non_default_hop() {
+    let mut map = HashMap::new();
+    map.insert(String::from("google"), String::from("https://example.com"));
+    assert_eq!(
+      resolve_hop("google hello world", &map, &None),
+      generate_route_result("https://example.com", "hello world"),
+    );
+  }
+}