add additional tests

src/args/arg.rs

@@ -3320,12 +3320,16 @@ impl<'a, 'b> Arg<'a, 'b> {
     /// will return `0` even though the [`ArgMatches::value_of`] will return the default specified.
     ///
     /// **NOTE:** If the user *does not* use this argument at runtime [`ArgMatches::is_present`] will
-    /// still return `true`. If you wish to determine whether the argument was used at runtime or
-    /// not, consider [`ArgMatches::occurrences_of`] which will return `0` if the argument was *not*
-    /// used at runtime.
+    /// return `true` if the variable is present in the environemnt . If you wish to determine whether
+    /// the argument was used at runtime or not, consider [`ArgMatches::occurrences_of`] which will
+    /// return `0` if the argument was *not* used at runtime.
     /// 
     /// **NOTE:** This implicitly sets [`Arg::takes_value(true)`].
     /// 
+    /// **NOTE:** If [`Arg::multiple(true)`] is set then [`Arg::use_delimiter(true)`] should also be
+    /// set. Otherwise, only a single argument will be returned from the environment variable. The
+    /// default delimiter is `,` and follows all the other delimiter rules.
+    ///  
     /// # Examples
     /// 
     /// In this example, we show the variable coming from the environment:
@@ -3344,7 +3348,6 @@ impl<'a, 'b> Arg<'a, 'b> {
     ///         "prog"
     ///     ]);
     ///
-    /// # env::remove_var("MY_FLAG");
     /// assert_eq!(m.value_of("flag"), Some("env"));
     /// ```
     /// 
@@ -3364,7 +3367,6 @@ impl<'a, 'b> Arg<'a, 'b> {
     ///         "prog", "--flag", "opt"
     ///     ]);
     ///
-    /// # env::remove_var("MY_FLAG");
     /// assert_eq!(m.value_of("flag"), Some("opt"));
     /// ```
     /// 
@@ -3386,9 +3388,29 @@ impl<'a, 'b> Arg<'a, 'b> {
     ///         "prog"
     ///     ]);
     ///
-    /// # env::remove_var("MY_FLAG");
     /// assert_eq!(m.value_of("flag"), Some("env"));
     /// ```
+    /// 
+    /// In this example, we show the use of multiple values in a single environment variable:
+    /// 
+    /// ```rust
+    /// # use std::env;
+    /// # use clap::{App, Arg};
+    ///
+    /// env::set_var("MY_FLAG_MULTI", "env1,env2");
+    ///  
+    /// let m = App::new("prog")
+    ///     .arg(Arg::with_name("flag")
+    ///         .long("flag")
+    ///         .env("MY_FLAG_MULTI")
+    ///         .multiple(true)
+    ///         .use_delimiter(true))
+    ///     .get_matches_from(vec![
+    ///         "prog"
+    ///     ]);
+    ///
+    /// assert_eq!(m.values_of("flag").unwrap().collect::<Vec<_>>(), vec!["env1", "env2"]);
+    /// ```
     pub fn env(self, name: &'a str) -> Self {
         self.env_os(OsStr::new(name))
     }

tests/env.rs

@@ -1,22 +1,186 @@
 extern crate clap;
-extern crate regex;
 
 use std::env;
 use std::ffi::OsStr;
 
-use clap::{App, Arg, ErrorKind};
+use clap::{App, Arg};
 
 #[test]
-fn env_no_default() {
+fn env() {
     env::set_var("CLP_TEST_ENV", "env");
 
     let r = App::new("df")
         .arg(Arg::from_usage("[arg] 'some opt'").env("CLP_TEST_ENV"))
         .get_matches_from_safe(vec![""]);
 
-    env::remove_var("CLP_TEST_ENV");
     assert!(r.is_ok());
     let m = r.unwrap();
-    // assert!(m.is_present("arg")); // TODO: should this be true?
+    assert!(m.is_present("arg"));
+    assert_eq!(m.occurrences_of("arg"), 0);
     assert_eq!(m.value_of("arg").unwrap(), "env");
 }
+
+#[test]
+fn env_os() {
+    env::set_var("CLP_TEST_ENV", "env");
+
+    let r = App::new("df")
+        .arg(
+            Arg::from_usage("[arg] 'some opt'").env_os(OsStr::new("CLP_TEST_ENV")),
+        )
+        .get_matches_from_safe(vec![""]);
+
+    assert!(r.is_ok());
+    let m = r.unwrap();
+    assert!(m.is_present("arg"));
+    assert_eq!(m.occurrences_of("arg"), 0);
+    assert_eq!(m.value_of("arg").unwrap(), "env");
+}
+
+#[test]
+fn no_env() {
+    // All the other tests use the presence of the Environment variable...
+    // we need another variable just in case one of the others is running at the same time...
+    env::remove_var("CLP_TEST_ENV_NONE");
+
+    let r = App::new("df")
+        .arg(Arg::from_usage("[arg] 'some opt'").env("CLP_TEST_ENV_NONE"))
+        .get_matches_from_safe(vec![""]);
+
+    assert!(r.is_ok());
+    let m = r.unwrap();
+    assert!(!m.is_present("arg"));
+    assert_eq!(m.occurrences_of("arg"), 0);
+    assert_eq!(m.value_of("arg"), None);
+}
+
+#[test]
+fn with_default() {
+    env::set_var("CLP_TEST_ENV", "env");
+
+    let r = App::new("df")
+        .arg(
+            Arg::from_usage("[arg] 'some opt'")
+                .env("CLP_TEST_ENV")
+                .default_value("default"),
+        )
+        .get_matches_from_safe(vec![""]);
+
+    assert!(r.is_ok());
+    let m = r.unwrap();
+    assert!(m.is_present("arg"));
+    assert_eq!(m.occurrences_of("arg"), 0);
+    assert_eq!(m.value_of("arg").unwrap(), "env");
+}
+
+#[test]
+fn opt_user_override() {
+    env::set_var("CLP_TEST_ENV", "env");
+
+    let r = App::new("df")
+        .arg(
+            Arg::from_usage("--arg [FILE] 'some arg'").env("CLP_TEST_ENV"),
+        )
+        .get_matches_from_safe(vec!["", "--arg", "opt"]);
+
+    assert!(r.is_ok());
+    let m = r.unwrap();
+    assert!(m.is_present("arg"));
+    assert_eq!(m.occurrences_of("arg"), 1);
+    assert_eq!(m.value_of("arg").unwrap(), "opt");
+}
+
+#[test]
+fn positionals() {
+    env::set_var("CLP_TEST_ENV", "env");
+
+    let r = App::new("df")
+        .arg(Arg::from_usage("[arg] 'some opt'").env("CLP_TEST_ENV"))
+        .get_matches_from_safe(vec![""]);
+
+    assert!(r.is_ok());
+    let m = r.unwrap();
+    assert!(m.is_present("arg"));
+    assert_eq!(m.occurrences_of("arg"), 0);
+    assert_eq!(m.value_of("arg").unwrap(), "env");
+}
+
+#[test]
+fn positionals_user_override() {
+    env::set_var("CLP_TEST_ENV", "env");
+
+    let r = App::new("df")
+        .arg(Arg::from_usage("[arg] 'some opt'").env("CLP_TEST_ENV"))
+        .get_matches_from_safe(vec!["", "opt"]);
+
+    assert!(r.is_ok());
+    let m = r.unwrap();
+    assert!(m.is_present("arg"));
+    assert_eq!(m.occurrences_of("arg"), 1);
+    assert_eq!(m.value_of("arg").unwrap(), "opt");
+}
+
+#[test]
+fn multiple_one() {
+    env::set_var("CLP_TEST_ENV", "env");
+
+    let r = App::new("df")
+        .arg(
+            Arg::from_usage("[arg] 'some opt'")
+                .env("CLP_TEST_ENV")
+                .use_delimiter(true)
+                .multiple(true),
+        )
+        .get_matches_from_safe(vec![""]);
+
+    assert!(r.is_ok());
+    let m = r.unwrap();
+    assert!(m.is_present("arg"));
+    assert_eq!(m.occurrences_of("arg"), 0);
+    assert_eq!(m.values_of("arg").unwrap().collect::<Vec<_>>(), vec!["env"]);
+}
+
+#[test]
+fn multiple_three() {
+    env::set_var("CLP_TEST_ENV_MULTI1", "env1,env2,env3");
+
+    let r = App::new("df")
+        .arg(
+            Arg::from_usage("[arg] 'some opt'")
+                .env("CLP_TEST_ENV_MULTI1")
+                .use_delimiter(true)
+                .multiple(true),
+        )
+        .get_matches_from_safe(vec![""]);
+
+    assert!(r.is_ok());
+    let m = r.unwrap();
+    assert!(m.is_present("arg"));
+    assert_eq!(m.occurrences_of("arg"), 0);
+    assert_eq!(
+        m.values_of("arg").unwrap().collect::<Vec<_>>(),
+        vec!["env1", "env2", "env3"]
+    );
+}
+
+#[test]
+fn multiple_no_delimiter() {
+    env::set_var("CLP_TEST_ENV_MULTI2", "env1 env2 env3");
+
+    let r = App::new("df")
+        .arg(
+            Arg::from_usage("[arg] 'some opt'")
+                .env("CLP_TEST_ENV_MULTI2")
+                .multiple(true),
+        )
+        .get_matches_from_safe(vec![""]);
+
+    assert!(r.is_ok());
+    let m = r.unwrap();
+    assert!(m.is_present("arg"));
+    assert_eq!(m.occurrences_of("arg"), 0);
+    assert_eq!(
+        m.values_of("arg").unwrap().collect::<Vec<_>>(),
+        vec!["env1 env2 env3"]
+    );
+}