Add Hook

src/symbols/hook.rs

@@ -0,0 +1,103 @@
+use std::error::Error;
+use std::fmt;
+
+use symbols::Symbol;
+
+pub struct Hook<A, B> where A: Symbol, B: Symbol {
+  a: A,
+  b: B
+}
+
+impl<A, B> Hook<A, B> where A: Symbol, B: Symbol {
+  pub fn new(a: A, b: B) -> Self {
+    Hook { a: a, b: b }
+  }
+}
+
+impl<A, B> Symbol for Hook<A, B> where A: Symbol, B: Symbol {
+  fn target_reached(&self) -> Result<bool, Box<Error>> {
+    self.a.target_reached().and_then(|reached| if reached { self.b.target_reached() } else { Ok(reached) })
+  }
+
+  fn execute(&self) -> Result<(), Box<Error>> {
+    try!(self.a.execute());
+    self.b.execute()
+  }
+}
+
+impl<A, B> fmt::Display for Hook<A, B> where A: Symbol, B: Symbol {
+  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error>{
+    write!(f, "Hook {} and then {}", self.a, self.b)
+  }
+}
+
+#[cfg(test)]
+mod test {
+  use std::error::Error;
+  use std::fmt;
+
+  use symbols::Symbol;
+  use symbols::hook::Hook;
+
+  struct ErrSymbol(String);
+  impl Symbol for ErrSymbol {
+    fn target_reached(&self) -> Result<bool, Box<Error>> { Err(self.0.clone().into()) }
+    fn execute(&self) -> Result<(), Box<Error>> { Err(self.0.clone().into()) }
+  }
+  impl fmt::Display for ErrSymbol { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error>{ write!(f, "") } }
+
+  struct OkSymbol(bool);
+  impl Symbol for OkSymbol {
+    fn target_reached(&self) -> Result<bool, Box<Error>> { Ok(self.0) }
+    fn execute(&self) -> Result<(), Box<Error>> { Ok(()) }
+  }
+  impl fmt::Display for OkSymbol { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error>{ write!(f, "") } }
+
+  #[test]
+  fn first_target_reached_fails() {
+    let res = Hook::new(ErrSymbol("first".into()), ErrSymbol("second".into())).target_reached();
+    assert_eq!(res.unwrap_err().description(), "first");
+  }
+
+  #[test]
+  fn first_target_not_reached() {
+    let res = Hook::new(OkSymbol(false), ErrSymbol("second".into())).target_reached();
+    assert_eq!(res.unwrap(), false);
+  }
+
+  #[test]
+  fn second_target_reached_fails() {
+    let res = Hook::new(OkSymbol(true), ErrSymbol("second".into())).target_reached();
+    assert_eq!(res.unwrap_err().description(), "second");
+  }
+
+  #[test]
+  fn second_target_not_reached() {
+    let res = Hook::new(OkSymbol(true), OkSymbol(false)).target_reached();
+    assert_eq!(res.unwrap(), false);
+  }
+
+  #[test]
+  fn everything_reached() {
+    let res = Hook::new(OkSymbol(true), OkSymbol(true)).target_reached();
+    assert_eq!(res.unwrap(), true);
+  }
+
+  #[test]
+  fn first_execute_fails() {
+    let res = Hook::new(ErrSymbol("first".into()), ErrSymbol("second".into())).execute();
+    assert_eq!(res.unwrap_err().description(), "first");
+  }
+
+  #[test]
+  fn second_execute_fails() {
+    let res = Hook::new(OkSymbol(true), ErrSymbol("second".into())).execute();
+    assert_eq!(res.unwrap_err().description(), "second");
+  }
+
+  #[test]
+  fn everything_executes() {
+    let res = Hook::new(OkSymbol(true), OkSymbol(true)).execute();
+    assert_eq!(res.unwrap(), ());
+  }
+}

src/symbols/mod.rs

@@ -18,3 +18,4 @@ pub mod npm;
 pub mod user;
 pub mod systemd;
 pub mod nginx;
+pub mod hook;