Added tests for cargo macros, fixes #1478

tests/app_from_crate.rs

@@ -0,0 +1,26 @@
+use clap::{app_from_crate, ErrorKind};
+
+static EVERYTHING: &str = "clap {{version}}
+Kevin K. <kbknapp@gmail.com>
+A simple to use, efficient, and full-featured Command Line Argument Parser
+
+USAGE:
+    clap
+
+FLAGS:
+    -h, --help       Prints help information
+    -V, --version    Prints version information
+";
+
+#[test]
+fn app_from_crate() {
+    let res = app_from_crate!().try_get_matches_from(vec!["clap", "--help"]);
+
+    assert!(res.is_err());
+    let err = res.unwrap_err();
+    assert_eq!(err.kind, ErrorKind::HelpDisplayed);
+    assert_eq!(
+        err.message,
+        EVERYTHING.replace("{{version}}", env!("CARGO_PKG_VERSION"))
+    );
+}

tests/cargo.rs

@@ -0,0 +1,71 @@
+use clap::{crate_authors, crate_description, crate_name, crate_version, App, ErrorKind};
+
+static DESCRIPTION_ONLY: &str = "prog 1
+A simple to use, efficient, and full-featured Command Line Argument Parser
+
+USAGE:
+    prog
+
+FLAGS:
+    -h, --help       Prints help information
+    -V, --version    Prints version information
+";
+
+static AUTHORS_ONLY: &str = "prog 1
+Kevin K. <kbknapp@gmail.com>
+
+USAGE:
+    prog
+
+FLAGS:
+    -h, --help       Prints help information
+    -V, --version    Prints version information
+";
+
+#[test]
+fn crate_version() {
+    let res = App::new("prog")
+        .version(crate_version!())
+        .try_get_matches_from(vec!["prog", "--version"]);
+
+    assert!(res.is_err());
+    let err = res.unwrap_err();
+    assert_eq!(err.kind, ErrorKind::VersionDisplayed);
+    assert_eq!(err.message, format!("prog {}", env!("CARGO_PKG_VERSION")));
+}
+
+#[test]
+fn crate_description() {
+    let res = App::new("prog")
+        .version("1")
+        .about(crate_description!())
+        .try_get_matches_from(vec!["prog", "--help"]);
+
+    assert!(res.is_err());
+    let err = res.unwrap_err();
+    assert_eq!(err.kind, ErrorKind::HelpDisplayed);
+    assert_eq!(err.message, DESCRIPTION_ONLY);
+}
+
+#[test]
+fn crate_authors() {
+    let res = App::new("prog")
+        .version("1")
+        .author(crate_authors!())
+        .try_get_matches_from(vec!["prog", "--help"]);
+
+    assert!(res.is_err());
+    let err = res.unwrap_err();
+    assert_eq!(err.kind, ErrorKind::HelpDisplayed);
+    assert_eq!(err.message, AUTHORS_ONLY);
+}
+
+#[test]
+fn crate_name() {
+    let res = App::new(crate_name!()).try_get_matches_from(vec!["clap", "--version"]);
+
+    assert!(res.is_err());
+    let err = res.unwrap_err();
+    assert_eq!(err.kind, ErrorKind::VersionDisplayed);
+    assert_eq!(err.message, "clap ");
+}