tests: reduce reliance on state in tests

This commit improves the integration test setup by running tests inside
the system's temporary directory instead of within ripgrep's `target`
directory. The motivation here is to attempt to reduce the effect of
unanticipated state on ripgrep's integration tests, such as the presence
of `.gitignore` files in ripgrep's checkout directory hierarchy
(including parent directories).

This doesn't remove all possible state. For example, there's no
guarantee that the system's temporary directory isn't itself within a
git repository. Moreover, there may still be other ignore rules in the
directory tree that might impact test behavior. Fixing this seems
somewhat difficult. Conceptually, it seems like ripgrep should run each
test in its own `chroot`-like environment, but doing this in a
non-annoying and portable way (including Windows) doesn't appear to be
possible.

Another approach to take here might be to teach ripgrep itself that a
particular directory should be treated as root, and therefore, never
look at anything outside that directory. This also seems complex to
implement, but tractable. Let's see how this approach works for now.

Fixes #448, #996

tests/tests.rs

@@ -590,6 +590,7 @@ sherlock!(no_ignore_hidden, "Sherlock", ".", |wd: WorkDir, mut cmd: Command| {
 });
 
 sherlock!(ignore_git, "Sherlock", ".", |wd: WorkDir, mut cmd: Command| {
+    wd.create_dir(".git");
     wd.create(".gitignore", "sherlock\n");
     wd.assert_err(&mut cmd);
 });
@@ -852,6 +853,7 @@ sherlock:but Doctor Watson has to have it taken out for him and dusted,
 
 // See: https://github.com/BurntSushi/ripgrep/issues/16
 clean!(regression_16, "xyz", ".", |wd: WorkDir, mut cmd: Command| {
+    wd.create_dir(".git");
     wd.create(".gitignore", "ghi/");
     wd.create_dir("ghi");
     wd.create_dir("def/ghi");
@@ -907,6 +909,7 @@ clean!(regression_50, "xyz", ".", |wd: WorkDir, mut cmd: Command| {
 
 // See: https://github.com/BurntSushi/ripgrep/issues/65
 clean!(regression_65, "xyz", ".", |wd: WorkDir, mut cmd: Command| {
+    wd.create_dir(".git");
     wd.create(".gitignore", "a/");
     wd.create_dir("a");
     wd.create("a/foo", "xyz");
@@ -916,6 +919,7 @@ clean!(regression_65, "xyz", ".", |wd: WorkDir, mut cmd: Command| {
 
 // See: https://github.com/BurntSushi/ripgrep/issues/67
 clean!(regression_67, "test", ".", |wd: WorkDir, mut cmd: Command| {
+    wd.create_dir(".git");
     wd.create(".gitignore", "/*\n!/dir");
     wd.create_dir("dir");
     wd.create_dir("foo");
@@ -928,6 +932,7 @@ clean!(regression_67, "test", ".", |wd: WorkDir, mut cmd: Command| {
 
 // See: https://github.com/BurntSushi/ripgrep/issues/87
 clean!(regression_87, "test", ".", |wd: WorkDir, mut cmd: Command| {
+    wd.create_dir(".git");
     wd.create(".gitignore", "foo\n**no-vcs**");
     wd.create("foo", "test");
     wd.assert_err(&mut cmd);
@@ -935,6 +940,7 @@ clean!(regression_87, "test", ".", |wd: WorkDir, mut cmd: Command| {
 
 // See: https://github.com/BurntSushi/ripgrep/issues/90
 clean!(regression_90, "test", ".", |wd: WorkDir, mut cmd: Command| {
+    wd.create_dir(".git");
     wd.create(".gitignore", "!.foo");
     wd.create(".foo", "test");
 
@@ -995,6 +1001,7 @@ clean!(regression_127, "Sherlock", ".", |wd: WorkDir, mut cmd: Command| {
     // ripgrep should ignore 'foo/sherlock' giving us results only from
     // 'foo/watson' but on Windows ripgrep will include both 'foo/sherlock' and
     // 'foo/watson' in the search results.
+    wd.create_dir(".git");
     wd.create(".gitignore", "foo/sherlock\n");
     wd.create_dir("foo");
     wd.create("foo/sherlock", hay::SHERLOCK);
@@ -1022,6 +1029,7 @@ clean!(regression_128, "x", ".", |wd: WorkDir, mut cmd: Command| {
 // TODO(burntsushi): Darwin doesn't like this test for some reason.
 #[cfg(not(target_os = "macos"))]
 clean!(regression_131, "test", ".", |wd: WorkDir, mut cmd: Command| {
+    wd.create_dir(".git");
     wd.create(".gitignore", "TopÑapa");
     wd.create("TopÑapa", "test");
     wd.assert_err(&mut cmd);
@@ -1309,6 +1317,7 @@ clean!(regression_599, "^$", "input.txt", |wd: WorkDir, mut cmd: Command| {
 
 // See: https://github.com/BurntSushi/ripgrep/issues/807
 clean!(regression_807, "test", ".", |wd: WorkDir, mut cmd: Command| {
+    wd.create_dir(".git");
     wd.create(".gitignore", ".a/b");
     wd.create_dir(".a/b");
     wd.create_dir(".a/c");

tests/workdir.rs

@@ -21,7 +21,8 @@ pub struct WorkDir {
     /// The directory in which this test executable is running.
     root: PathBuf,
     /// The directory in which the test should run. If a test needs to create
-    /// files, they should go in here.
+    /// files, they should go in here. This directory is also used as the CWD
+    /// for any processes created by the test.
     dir: PathBuf,
 }
 
@@ -31,9 +32,15 @@ impl WorkDir {
     /// to a logical grouping of tests.
     pub fn new(name: &str) -> WorkDir {
         let id = NEXT_ID.fetch_add(1, Ordering::SeqCst);
-        let root = env::current_exe().unwrap()
+        let root = env::current_exe()
-            .parent().expect("executable's directory").to_path_buf();
+            .unwrap()
-        let dir = root.join(TEST_DIR).join(name).join(&format!("{}", id));
+            .parent()
+            .expect("executable's directory")
+            .to_path_buf();
+        let dir = env::temp_dir()
+            .join(TEST_DIR)
+            .join(name)
+            .join(&format!("{}", id));
         nice_err(&dir, repeat(|| fs::create_dir_all(&dir)));
         WorkDir {
             root: root,
@@ -107,28 +114,11 @@ impl WorkDir {
     }
 
     /// Returns the path to the ripgrep executable.
-    #[cfg(not(windows))]
     pub fn bin(&self) -> PathBuf {
-        let path = self.root.join("rg");
+        if cfg!(windows) {
-        if !path.is_file() {
-            // Looks like a recent version of Cargo changed the cwd or the
-            // location of the test executable.
-            self.root.join("../rg")
-        } else {
-            path
-        }
-    }
-
-    /// Returns the path to the ripgrep executable.
-    #[cfg(windows)]
-    pub fn bin(&self) -> PathBuf {
-        let path = self.root.join("rg.exe");
-        if !path.is_file() {
-            // Looks like a recent version of Cargo changed the cwd or the
-            // location of the test executable.
             self.root.join("../rg.exe")
         } else {
-            path
+            self.root.join("../rg")
         }
     }