tests: disable some chgrp tests when part of the root group

Some tests failed when run using Docker because they assumed the
user would never be root.  This is more of a band-aid solution.
An actual fix would be to test see if something like these tests
were to succeed when the user is root.

Cargo.toml

@@ -252,6 +252,7 @@ unindent = "0.1.0"
 lazy_static = "0.2.2"
 
 [target.'cfg(unix)'.dev-dependencies]
+rust-users = { git = "https://github.com/Arcterus/rust-users" }
 unix_socket = "0.5.0"
 
 [[bin]]

src/stdbuf/build.rs

@@ -18,8 +18,11 @@ mod platform {
 fn main() {
     mkmain::main();
 
+    let manifest_dir = env::var("CARGO_MANIFEST_DIR").expect("Could not find manifest dir");
+    let profile = env::var("PROFILE").expect("Could not determine profile");
+
     let out_dir = env::var("OUT_DIR").unwrap();
-    let libstdbuf = format!("{}/../../{}/{}/deps/liblibstdbuf{}", env::var("CARGO_MANIFEST_DIR").unwrap(), env::var("CARGO_TARGET_DIR").unwrap_or("target".to_string()), env::var("PROFILE").unwrap(), platform::DYLIB_EXT);
+    let libstdbuf = format!("{}/../../{}/{}/deps/liblibstdbuf{}", manifest_dir, env::var("CARGO_TARGET_DIR").unwrap_or("target".to_string()), profile, platform::DYLIB_EXT);
     
     fs::copy(libstdbuf, Path::new(&out_dir).join("libstdbuf.so")).unwrap();
 }

tests/test_chgrp.rs

@@ -1,5 +1,5 @@
 use common::util::*;
-
+use rust_users::*;
 
 #[test]
 fn test_invalid_option() {
@@ -14,30 +14,34 @@ static DIR: &'static str = "/tmp";
 #[test]
 fn test_invalid_group() {
     new_ucmd!()
-        .arg("nosuchgroup")
+        .arg("__nosuchgroup__")
         .arg("/")
         .fails()
-        .stderr_is("chgrp: invalid group: nosuchgroup");
+        .stderr_is("chgrp: invalid group: __nosuchgroup__");
 }
 
 #[test]
 fn test_1() {
-    new_ucmd!()
-        .arg("bin")
-        .arg(DIR)
-        .fails()
-        .stderr_is("chgrp: changing group of '/tmp': Operation not permitted (os error 1)");
+    if get_effective_gid() != 0 {
+        new_ucmd!()
+            .arg("bin")
+            .arg(DIR)
+            .fails()
+            .stderr_is("chgrp: changing group of '/tmp': Operation not permitted (os error 1)");
+    }
 }
 
 #[test]
 fn test_fail_silently() {
-    for opt in &["-f", "--silent", "--quiet"] {
-        new_ucmd!()
-            .arg(opt)
-            .arg("bin")
-            .arg(DIR)
-            .run()
-            .fails_silently();
+    if get_effective_gid() != 0 {
+        for opt in &["-f", "--silent", "--quiet"] {
+            new_ucmd!()
+                .arg(opt)
+                .arg("bin")
+                .arg(DIR)
+                .run()
+                .fails_silently();
+        }
     }
 }
 
@@ -94,13 +98,15 @@ fn test_preserve_root_symlink() {
 #[test]
 #[cfg(target_os = "linux")]
 fn test_reference() {
-    new_ucmd!()
-        .arg("-v")
-        .arg("--reference=/etc/passwd")
-        .arg("/etc")
-        .fails()
-        .stderr_is("chgrp: changing group of '/etc': Operation not permitted (os error 1)\n")
-        .stdout_is("failed to change group of /etc from root to root\n");
+    if get_effective_gid() != 0 {
+        new_ucmd!()
+            .arg("-v")
+            .arg("--reference=/etc/passwd")
+            .arg("/etc")
+            .fails()
+            .stderr_is("chgrp: changing group of '/etc': Operation not permitted (os error 1)\n")
+            .stdout_is("failed to change group of /etc from root to root\n");
+    }
 }
 
 #[test]
@@ -116,23 +122,27 @@ fn test_reference() {
 #[test]
 #[cfg(target_os = "linux")]
 fn test_big_p() {
-    new_ucmd!()
-        .arg("-RP")
-        .arg("bin")
-        .arg("/proc/self/cwd")
-        .fails()
-        .stderr_is("chgrp: changing group of '/proc/self/cwd': Operation not permitted (os error 1)\n");
+    if get_effective_gid() != 0 {
+        new_ucmd!()
+            .arg("-RP")
+            .arg("bin")
+            .arg("/proc/self/cwd")
+            .fails()
+            .stderr_is("chgrp: changing group of '/proc/self/cwd': Operation not permitted (os error 1)\n");
+    }
 }
 
 #[test]
 #[cfg(target_os = "linux")]
 fn test_big_h() {
-    assert!(new_ucmd!()
-        .arg("-RH")
-        .arg("bin")
-        .arg("/proc/self/fd")
-        .fails()
-        .stderr
-        .lines()
-        .fold(0, |acc, _| acc + 1) > 1);
+    if get_effective_gid() != 0 {
+        assert!(new_ucmd!()
+            .arg("-RH")
+            .arg("bin")
+            .arg("/proc/self/fd")
+            .fails()
+            .stderr
+            .lines()
+            .fold(0, |acc, _| acc + 1) > 1);
+    }
 }

tests/tests.rs

@@ -4,6 +4,9 @@ mod common;
 #[macro_use]
 extern crate lazy_static;
 
+#[cfg(unix)]
+extern crate rust_users;
+
 // For conditional compilation
 macro_rules! unix_only {
     ($($fea:expr, $m:ident);+) => {