Spack core and tests no longer use `os.chdir()`

- Spack's core package interface was previously overly stateful, in that
  calling methods like `do_stage()` could change your working directory.

- This removes Stage's `chdir` and `chdir_to_source` methods and replaces
  their usages with `with working_dir(stage.path)` and `with
  working_dir(stage.source_path)`, respectively.  These ensure the
  original working directory is preserved.

- This not only makes the API more usable, it makes the tests more
  deterministic, as previously a test could leave the current working
  directory in a bad state and cause subsequent tests to fail
  mysteriously.

14 files changed, 393 insertions, 450 deletions

diff --git a/lib/spack/spack/cmd/clone.py b/lib/spack/spack/cmd/clone.py
index 19201b1f86..79b62c44ff 100644
--- a/lib/spack/spack/cmd/clone.py
+++ b/lib/spack/spack/cmd/clone.py
@@ -25,7 +25,7 @@
 import os
 
 import llnl.util.tty as tty
-from llnl.util.filesystem import join_path, mkdirp
+from llnl.util.filesystem import mkdirp, working_dir
 
 import spack
 from spack.util.executable import ProcessError, which
@@ -47,7 +47,7 @@ def setup_parser(subparser):
 
 
 def get_origin_info(remote):
-    git_dir = join_path(spack.prefix, '.git')
+    git_dir = os.path.join(spack.prefix, '.git')
     git = which('git', required=True)
     try:
         branch = git('symbolic-ref', '--short', 'HEAD', output=str)
@@ -81,7 +81,7 @@ def clone(parser, args):
 
     mkdirp(prefix)
 
-    if os.path.exists(join_path(prefix, '.git')):
+    if os.path.exists(os.path.join(prefix, '.git')):
         tty.die("There already seems to be a git repository in %s" % prefix)
 
     files_in_the_way = os.listdir(prefix)
@@ -94,14 +94,14 @@ def clone(parser, args):
             "%s/bin/spack" % prefix,
             "%s/lib/spack/..." % prefix)
 
-    os.chdir(prefix)
-    git = which('git', required=True)
-    git('init', '--shared', '-q')
-    git('remote', 'add', 'origin', origin_url)
-    git('fetch', 'origin', '%s:refs/remotes/origin/%s' % (branch, branch),
-                           '-n', '-q')
-    git('reset', '--hard', 'origin/%s' % branch, '-q')
-    git('checkout', '-B', branch, 'origin/%s' % branch, '-q')
-
-    tty.msg("Successfully created a new spack in %s" % prefix,
-            "Run %s/bin/spack to use this installation." % prefix)
+    with working_dir(prefix):
+        git = which('git', required=True)
+        git('init', '--shared', '-q')
+        git('remote', 'add', 'origin', origin_url)
+        git('fetch', 'origin', '%s:refs/remotes/origin/%s' % (branch, branch),
+            '-n', '-q')
+        git('reset', '--hard', 'origin/%s' % branch, '-q')
+        git('checkout', '-B', branch, 'origin/%s' % branch, '-q')
+
+        tty.msg("Successfully created a new spack in %s" % prefix,
+                "Run %s/bin/spack to use this installation." % prefix)
diff --git a/lib/spack/spack/fetch_strategy.py b/lib/spack/spack/fetch_strategy.py
index bc9030ba8c..867d73d0a3 100644
--- a/lib/spack/spack/fetch_strategy.py
+++ b/lib/spack/spack/fetch_strategy.py
@@ -153,16 +153,15 @@ class FetchStrategy(with_metaclass(FSMeta, object)):
 
 @pattern.composite(interface=FetchStrategy)
 class FetchStrategyComposite(object):
+    """Composite for a FetchStrategy object.
 
-    """
-    Composite for a FetchStrategy object. Implements the GoF composite pattern.
+    Implements the GoF composite pattern.
     """
     matches = FetchStrategy.matches
     set_stage = FetchStrategy.set_stage
 
 
 class URLFetchStrategy(FetchStrategy):
-
     """FetchStrategy that pulls source code from a URL for an archive,
        checks the archive against a checksum,and decompresses the archive.
     """
@@ -200,8 +199,6 @@ class URLFetchStrategy(FetchStrategy):
 
     @_needs_stage
     def fetch(self):
-        self.stage.chdir()
-
         if self.archive_file:
             tty.msg("Already downloaded %s" % self.archive_file)
             return
@@ -242,7 +239,8 @@ class URLFetchStrategy(FetchStrategy):
 
         # Run curl but grab the mime type from the http headers
         curl = self.curl
-        headers = curl(*curl_args, output=str, fail_on_error=False)
+        with working_dir(self.stage.path):
+            headers = curl(*curl_args, output=str, fail_on_error=False)
 
         if curl.returncode != 0:
             # clean up archive on failure.
@@ -310,7 +308,6 @@ class URLFetchStrategy(FetchStrategy):
 
         tty.msg("Staging archive: %s" % self.archive_file)
 
-        self.stage.chdir()
         if not self.archive_file:
             raise NoArchiveFileError(
                 "Couldn't find archive file",
@@ -318,15 +315,17 @@ class URLFetchStrategy(FetchStrategy):
 
         if not self.extension:
             self.extension = extension(self.archive_file)
+
         decompress = decompressor_for(self.archive_file, self.extension)
 
         # Expand all tarballs in their own directory to contain
         # exploding tarballs.
         tarball_container = os.path.join(self.stage.path,
                                          "spack-expanded-archive")
+
         mkdirp(tarball_container)
-        os.chdir(tarball_container)
-        decompress(self.archive_file)
+        with working_dir(tarball_container):
+            decompress(self.archive_file)
 
         # Check for an exploding tarball, i.e. one that doesn't expand
         # to a single directory.  If the tarball *didn't* explode,
@@ -345,10 +344,9 @@ class URLFetchStrategy(FetchStrategy):
                     shutil.move(os.path.join(tarball_container, f),
                                 os.path.join(self.stage.path, f))
                 os.rmdir(tarball_container)
+
         if not files:
             os.rmdir(tarball_container)
-        # Set the wd back to the stage when done.
-        self.stage.chdir()
 
     def archive(self, destination):
         """Just moves this archive to the destination."""
@@ -416,8 +414,6 @@ class CacheURLFetchStrategy(URLFetchStrategy):
         if not os.path.isfile(path):
             raise NoCacheError('No cache of %s' % path)
 
-        self.stage.chdir()
-
         # remove old symlink if one is there.
         filename = self.stage.save_filename
         if os.path.exists(filename):
@@ -484,8 +480,8 @@ class VCSFetchStrategy(FetchStrategy):
             for p in patterns:
                 tar.add_default_arg('--exclude=%s' % p)
 
-        self.stage.chdir()
-        tar('-czf', destination, os.path.basename(self.stage.source_path))
+        with working_dir(self.stage.path):
+            tar('-czf', destination, os.path.basename(self.stage.source_path))
 
     def __str__(self):
         return "VCS: %s" % self.url
@@ -495,9 +491,8 @@ class VCSFetchStrategy(FetchStrategy):
 
 
 class GoFetchStrategy(VCSFetchStrategy):
+    """Fetch strategy that employs the `go get` infrastructure.
 
-    """
-    Fetch strategy that employs the `go get` infrastructure
     Use like this in a package:
 
        version('name',
@@ -530,25 +525,24 @@ class GoFetchStrategy(VCSFetchStrategy):
 
     @_needs_stage
     def fetch(self):
-        self.stage.chdir()
-
         tty.msg("Trying to get go resource:", self.url)
 
-        try:
-            os.mkdir('go')
-        except OSError:
-            pass
-        env = dict(os.environ)
-        env['GOPATH'] = os.path.join(os.getcwd(), 'go')
-        self.go('get', '-v', '-d', self.url, env=env)
+        with working_dir(self.stage.path):
+            try:
+                os.mkdir('go')
+            except OSError:
+                pass
+            env = dict(os.environ)
+            env['GOPATH'] = os.path.join(os.getcwd(), 'go')
+            self.go('get', '-v', '-d', self.url, env=env)
 
     def archive(self, destination):
         super(GoFetchStrategy, self).archive(destination, exclude='.git')
 
     @_needs_stage
     def reset(self):
-        self.stage.chdir_to_source()
-        self.go('clean')
+        with working_dir(self.stage.source_path):
+            self.go('clean')
 
     def __str__(self):
         return "[go] %s" % self.url
@@ -607,10 +601,7 @@ class GitFetchStrategy(VCSFetchStrategy):
     def cachable(self):
         return bool(self.commit or self.tag)
 
-    @_needs_stage
     def fetch(self):
-        self.stage.chdir()
-
         if self.stage.source_path:
             tty.msg("Already fetched %s" % self.stage.source_path)
             return
@@ -622,20 +613,24 @@ class GitFetchStrategy(VCSFetchStrategy):
             args = 'at tag %s' % self.tag
         elif self.branch:
             args = 'on branch %s' % self.branch
+
         tty.msg("Trying to clone git repository: %s %s" % (self.url, args))
 
+        git = self.git
         if self.commit:
             # Need to do a regular clone and check out everything if
             # they asked for a particular commit.
-            if spack.debug:
-                self.git('clone', self.url)
-            else:
-                self.git('clone', '--quiet', self.url)
-            self.stage.chdir_to_source()
-            if spack.debug:
-                self.git('checkout', self.commit)
-            else:
-                self.git('checkout', '--quiet', self.commit)
+            with working_dir(self.stage.path):
+                if spack.debug:
+                    git('clone', self.url)
+                else:
+                    git('clone', '--quiet', self.url)
+
+            with working_dir(self.stage.source_path):
+                if spack.debug:
+                    git('checkout', self.commit)
+                else:
+                    git('checkout', '--quiet', self.commit)
 
         else:
             # Can be more efficient if not checking out a specific commit.
@@ -654,57 +649,58 @@ class GitFetchStrategy(VCSFetchStrategy):
             if self.git_version > ver('1.7.10'):
                 args.append('--single-branch')
 
-            cloned = False
-            # Yet more efficiency, only download a 1-commit deep tree
-            if self.git_version >= ver('1.7.1'):
-                try:
-                    self.git(*(args + ['--depth', '1', self.url]))
-                    cloned = True
-                except spack.error.SpackError:
-                    # This will fail with the dumb HTTP transport
-                    # continue and try without depth, cleanup first
-                    pass
-
-            if not cloned:
-                args.append(self.url)
-                self.git(*args)
-
-            self.stage.chdir_to_source()
-
-            # For tags, be conservative and check them out AFTER
-            # cloning.  Later git versions can do this with clone
-            # --branch, but older ones fail.
-            if self.tag and self.git_version < ver('1.8.5.2'):
-                # pull --tags returns a "special" error code of 1 in
-                # older versions that we have to ignore.
-                # see: https://github.com/git/git/commit/19d122b
+            with working_dir(self.stage.path):
+                cloned = False
+                # Yet more efficiency, only download a 1-commit deep tree
+                if self.git_version >= ver('1.7.1'):
+                    try:
+                        git(*(args + ['--depth', '1', self.url]))
+                        cloned = True
+                    except spack.error.SpackError:
+                        # This will fail with the dumb HTTP transport
+                        # continue and try without depth, cleanup first
+                        pass
+
+                if not cloned:
+                    args.append(self.url)
+                    git(*args)
+
+                with working_dir(self.stage.source_path):
+                    # For tags, be conservative and check them out AFTER
+                    # cloning.  Later git versions can do this with clone
+                    # --branch, but older ones fail.
+                    if self.tag and self.git_version < ver('1.8.5.2'):
+                        # pull --tags returns a "special" error code of 1 in
+                        # older versions that we have to ignore.
+                        # see: https://github.com/git/git/commit/19d122b
+                        if spack.debug:
+                            git('pull', '--tags', ignore_errors=1)
+                            git('checkout', self.tag)
+                        else:
+                            git('pull', '--quiet', '--tags', ignore_errors=1)
+                            git('checkout', '--quiet', self.tag)
+
+        with working_dir(self.stage.source_path):
+            # Init submodules if the user asked for them.
+            if self.submodules:
                 if spack.debug:
-                    self.git('pull', '--tags', ignore_errors=1)
-                    self.git('checkout', self.tag)
+                    git('submodule', 'update', '--init', '--recursive')
                 else:
-                    self.git('pull', '--quiet', '--tags', ignore_errors=1)
-                    self.git('checkout', '--quiet', self.tag)
-
-        # Init submodules if the user asked for them.
-        if self.submodules:
-            if spack.debug:
-                self.git('submodule', 'update', '--init', '--recursive')
-            else:
-                self.git('submodule', '--quiet', 'update', '--init',
-                         '--recursive')
+                    git('submodule', '--quiet', 'update', '--init',
+                        '--recursive')
 
     def archive(self, destination):
         super(GitFetchStrategy, self).archive(destination, exclude='.git')
 
     @_needs_stage
     def reset(self):
-        self.stage.chdir_to_source()
-        if spack.debug:
-            self.git('checkout', '.')
-            self.git('clean', '-f')
-        else:
-            self.git('checkout', '--quiet', '.')
-            self.git('clean', '--quiet', '-f')
+        with working_dir(self.stage.source_path):
+            if spack.debug:
+                self.git('checkout', '.')
+                self.git('clean', '-f')
+            else:
+                self.git('checkout', '--quiet', '.')
+                self.git('clean', '--quiet', '-f')
 
     def __str__(self):
         return "[git] %s" % self.url
@@ -749,8 +745,6 @@ class SvnFetchStrategy(VCSFetchStrategy):
 
     @_needs_stage
     def fetch(self):
-        self.stage.chdir()
-
         if self.stage.source_path:
             tty.msg("Already fetched %s" % self.stage.source_path)
             return
@@ -762,30 +756,31 @@ class SvnFetchStrategy(VCSFetchStrategy):
             args += ['-r', self.revision]
         args.append(self.url)
 
-        self.svn(*args)
-        self.stage.chdir_to_source()
+        with working_dir(self.stage.path):
+            self.svn(*args)
 
     def _remove_untracked_files(self):
         """Removes untracked files in an svn repository."""
-        status = self.svn('status', '--no-ignore', output=str)
-        self.svn('status', '--no-ignore')
-        for line in status.split('\n'):
-            if not re.match('^[I?]', line):
-                continue
-            path = line[8:].strip()
-            if os.path.isfile(path):
-                os.unlink(path)
-            elif os.path.isdir(path):
-                shutil.rmtree(path, ignore_errors=True)
+        with working_dir(self.stage.source_path):
+            status = self.svn('status', '--no-ignore', output=str)
+            self.svn('status', '--no-ignore')
+            for line in status.split('\n'):
+                if not re.match('^[I?]', line):
+                    continue
+                path = line[8:].strip()
+                if os.path.isfile(path):
+                    os.unlink(path)
+                elif os.path.isdir(path):
+                    shutil.rmtree(path, ignore_errors=True)
 
     def archive(self, destination):
         super(SvnFetchStrategy, self).archive(destination, exclude='.svn')
 
     @_needs_stage
     def reset(self):
-        self.stage.chdir_to_source()
         self._remove_untracked_files()
-        self.svn('revert', '.', '-R')
+        with working_dir(self.stage.source_path):
+            self.svn('revert', '.', '-R')
 
     def __str__(self):
         return "[svn] %s" % self.url
@@ -845,8 +840,6 @@ class HgFetchStrategy(VCSFetchStrategy):
 
     @_needs_stage
     def fetch(self):
-        self.stage.chdir()
-
         if self.stage.source_path:
             tty.msg("Already fetched %s" % self.stage.source_path)
             return
@@ -866,27 +859,26 @@ class HgFetchStrategy(VCSFetchStrategy):
         if self.revision:
             args.extend(['-r', self.revision])
 
-        self.hg(*args)
+        with working_dir(self.stage.path):
+            self.hg(*args)
 
     def archive(self, destination):
         super(HgFetchStrategy, self).archive(destination, exclude='.hg')
 
     @_needs_stage
     def reset(self):
-        self.stage.chdir()
-
-        source_path = self.stage.source_path
-        scrubbed = "scrubbed-source-tmp"
+        with working_dir(self.stage.path):
+            source_path = self.stage.source_path
+            scrubbed = "scrubbed-source-tmp"
 
-        args = ['clone']
-        if self.revision:
-            args += ['-r', self.revision]
-        args += [source_path, scrubbed]
-        self.hg(*args)
+            args = ['clone']
+            if self.revision:
+                args += ['-r', self.revision]
+            args += [source_path, scrubbed]
+            self.hg(*args)
 
-        shutil.rmtree(source_path, ignore_errors=True)
-        shutil.move(scrubbed, source_path)
-        self.stage.chdir_to_source()
+            shutil.rmtree(source_path, ignore_errors=True)
+            shutil.move(scrubbed, source_path)
 
     def __str__(self):
         return "[hg] %s" % self.url
diff --git a/lib/spack/spack/package.py b/lib/spack/spack/package.py
index 4bcfa9703e..f895b4b6fb 100644
--- a/lib/spack/spack/package.py
+++ b/lib/spack/spack/package.py
@@ -984,14 +984,15 @@ class PackageBase(with_metaclass(PackageMeta, object)):
         self.stage.cache_local()
 
     def do_stage(self, mirror_only=False):
-        """Unpacks the fetched tarball, then changes into the expanded tarball
-           directory."""
+        """Unpacks and expands the fetched tarball."""
         if not self.spec.concrete:
             raise ValueError("Can only stage concrete packages.")
 
         self.do_fetch(mirror_only)
         self.stage.expand_archive()
-        self.stage.chdir_to_source()
+
+        if not os.listdir(self.stage.path):
+            raise FetchError("Archive was empty for %s" % self.name)
 
     @classmethod
     def lookup_patch(cls, sha256):
@@ -1059,8 +1060,6 @@ class PackageBase(with_metaclass(PackageMeta, object)):
             tty.msg("Patching failed last time. Restaging.")
             self.stage.restage()
 
-        self.stage.chdir_to_source()
-
         # If this file exists, then we already applied all the patches.
         if os.path.isfile(good_file):
             tty.msg("Already patched %s" % self.name)
@@ -1073,7 +1072,8 @@ class PackageBase(with_metaclass(PackageMeta, object)):
         patched = False
         for patch in patches:
             try:
-                patch.apply(self.stage)
+                with working_dir(self.stage.source_path):
+                    patch.apply(self.stage)
                 tty.msg('Applied patch %s' % patch.path_or_url)
                 patched = True
             except:
@@ -1084,7 +1084,8 @@ class PackageBase(with_metaclass(PackageMeta, object)):
 
         if has_patch_fun:
             try:
-                self.patch()
+                with working_dir(self.stage.source_path):
+                    self.patch()
                 tty.msg("Ran patch() for %s" % self.name)
                 patched = True
             except spack.multimethod.NoSuchMethodError:
@@ -1384,23 +1385,23 @@ class PackageBase(with_metaclass(PackageMeta, object)):
                         install_tree(self.stage.source_path, src_target)
 
                     # Do the real install in the source directory.
-                    self.stage.chdir_to_source()
-
-                    # Save the build environment in a file before building.
-                    dump_environment(self.env_path)
-
-                    # Spawn a daemon that reads from a pipe and redirects
-                    # everything to log_path
-                    with log_output(self.log_path, echo, True) as logger:
-                        for phase_name, phase_attr in zip(
-                                self.phases, self._InstallPhase_phases):
-
-                            with logger.force_echo():
-                                tty.msg("Executing phase: '%s'" % phase_name)
-
-                            # Redirect stdout and stderr to daemon pipe
-                            phase = getattr(self, phase_attr)
-                            phase(self.spec, self.prefix)
+                    with working_dir(self.stage.source_path):
+                        # Save the build environment in a file before building.
+                        dump_environment(self.env_path)
+
+                        # Spawn a daemon that reads from a pipe and redirects
+                        # everything to log_path
+                        with log_output(self.log_path, echo, True) as logger:
+                            for phase_name, phase_attr in zip(
+                                    self.phases, self._InstallPhase_phases):
+
+                                with logger.force_echo():
+                                    tty.msg(
+                                        "Executing phase: '%s'" % phase_name)
+
+                                # Redirect stdout and stderr to daemon pipe
+                                phase = getattr(self, phase_attr)
+                                phase(self.spec, self.prefix)
 
                     echo = logger.echo
                     self.log()
diff --git a/lib/spack/spack/stage.py b/lib/spack/spack/stage.py
index d0072b25e2..1d80eb9879 100644
--- a/lib/spack/spack/stage.py
+++ b/lib/spack/spack/stage.py
@@ -366,18 +366,8 @@ class Stage(object):
                 return p
         return None
 
-    def chdir(self):
-        """Changes directory to the stage path. Or dies if it is not set
-        up."""
-        if os.path.isdir(self.path):
-            os.chdir(self.path)
-        else:
-            raise ChdirError("Setup failed: no such directory: " + self.path)
-
     def fetch(self, mirror_only=False):
         """Downloads an archive or checks out code from a repository."""
-        self.chdir()
-
         fetchers = []
         if not mirror_only:
             fetchers.append(self.default_fetcher)
@@ -478,18 +468,6 @@ class Stage(object):
         else:
             tty.msg("Already staged %s in %s" % (self.name, self.path))
 
-    def chdir_to_source(self):
-        """Changes directory to the expanded archive directory.
-           Dies with an error if there was no expanded archive.
-        """
-        path = self.source_path
-        if not path:
-            raise StageError("Attempt to chdir before expanding archive.")
-        else:
-            os.chdir(path)
-            if not os.listdir(path):
-                raise StageError("Archive was empty for %s" % self.name)
-
     def restage(self):
         """Removes the expanded archive path if it exists, then re-expands
            the archive.
@@ -613,9 +591,6 @@ class StageComposite:
     def path(self):
         return self[0].path
 
-    def chdir_to_source(self):
-        return self[0].chdir_to_source()
-
     @property
     def archive_file(self):
         return self[0].archive_file
@@ -634,12 +609,6 @@ class DIYStage(object):
         self.source_path = path
         self.created = True
 
-    def chdir(self):
-        if os.path.isdir(self.path):
-            os.chdir(self.path)
-        else:
-            raise ChdirError("Setup failed: no such directory: " + self.path)
-
     # DIY stages do nothing as context managers.
     def __enter__(self):
         pass
@@ -647,9 +616,6 @@ class DIYStage(object):
     def __exit__(self, exc_type, exc_val, exc_tb):
         pass
 
-    def chdir_to_source(self):
-        self.chdir()
-
     def fetch(self, *args, **kwargs):
         tty.msg("No need to fetch for DIY.")
 
@@ -701,9 +667,5 @@ class RestageError(StageError):
     """"Error encountered during restaging."""
 
 
-class ChdirError(StageError):
-    """Raised when Spack can't change directories."""
-
-
 # Keep this in namespace for convenience
 FailedDownloadError = fs.FailedDownloadError
diff --git a/lib/spack/spack/test/cmd/install.py b/lib/spack/spack/test/cmd/install.py
index cb39e62cf8..7a04b59748 100644
--- a/lib/spack/spack/test/cmd/install.py
+++ b/lib/spack/spack/test/cmd/install.py
@@ -57,8 +57,8 @@ def test_install_package_and_dependency(
         tmpdir, builtin_mock, mock_archive, mock_fetch, config,
         install_mockery):
 
-    tmpdir.chdir()
-    install('--log-format=junit', '--log-file=test.xml', 'libdwarf')
+    with tmpdir.as_cwd():
+        install('--log-format=junit', '--log-file=test.xml', 'libdwarf')
 
     files = tmpdir.listdir()
     filename = tmpdir.join('test.xml')
@@ -104,9 +104,9 @@ def test_install_package_already_installed(
         tmpdir, builtin_mock, mock_archive, mock_fetch, config,
         install_mockery):
 
-    tmpdir.chdir()
-    install('libdwarf')
-    install('--log-format=junit', '--log-file=test.xml', 'libdwarf')
+    with tmpdir.as_cwd():
+        install('libdwarf')
+        install('--log-format=junit', '--log-file=test.xml', 'libdwarf')
 
     files = tmpdir.listdir()
     filename = tmpdir.join('test.xml')
diff --git a/lib/spack/spack/test/conftest.py b/lib/spack/spack/test/conftest.py
index 80e93e8944..85f52e9d0e 100644
--- a/lib/spack/spack/test/conftest.py
+++ b/lib/spack/spack/test/conftest.py
@@ -49,9 +49,28 @@ from spack.spec import Spec
 from spack.version import Version
 
 
-##########
-# Monkey-patching that is applied to all tests
-##########
+#
+# These fixtures are applied to all tests
+#
+@pytest.fixture(scope='function', autouse=True)
+def no_chdir():
+    """Ensure that no test changes Spack's working dirctory.
+
+    This prevents Spack tests (and therefore Spack commands) from
+    changing the working directory and causing other tests to fail
+    mysteriously. Tests should use ``working_dir`` or ``py.path``'s
+    ``.as_cwd()`` instead of ``os.chdir`` to avoid failing this check.
+
+    We assert that the working directory hasn't changed, unless the
+    original wd somehow ceased to exist.
+
+    """
+    original_wd = os.getcwd()
+    yield
+    if os.path.isdir(original_wd):
+        assert os.getcwd() == original_wd
+
+
 @pytest.fixture(autouse=True)
 def mock_fetch_cache(monkeypatch):
     """Substitutes spack.fetch_cache with a mock object that does nothing
@@ -200,12 +219,11 @@ def database(tmpdir_factory, builtin_mock, config):
 
     # Make a fake install directory
     install_path = tmpdir_factory.mktemp('install_for_database')
-    spack_install_path = py.path.local(spack.store.root)
-    spack.store.root = str(install_path)
+    spack_install_path = spack.store.root
 
+    spack.store.root = str(install_path)
     install_layout = spack.directory_layout.YamlDirectoryLayout(
-        str(install_path)
-    )
+        str(install_path))
     spack_install_layout = spack.store.layout
     spack.store.layout = install_layout
 
@@ -216,14 +234,12 @@ def database(tmpdir_factory, builtin_mock, config):
 
     Entry = collections.namedtuple('Entry', ['path', 'layout', 'db'])
     Database = collections.namedtuple(
-        'Database', ['real', 'mock', 'install', 'uninstall', 'refresh']
-    )
+        'Database', ['real', 'mock', 'install', 'uninstall', 'refresh'])
 
     real = Entry(
         path=spack_install_path,
         layout=spack_install_layout,
-        db=spack_install_db
-    )
+        db=spack_install_db)
     mock = Entry(path=install_path, layout=install_layout, db=install_db)
 
     def _install(spec):
@@ -249,8 +265,8 @@ def database(tmpdir_factory, builtin_mock, config):
         mock=mock,
         install=_install,
         uninstall=_uninstall,
-        refresh=_refresh
-    )
+        refresh=_refresh)
+
     # Transaction used to avoid repeated writes.
     with spack.store.db.write_transaction():
         t.install('mpileaks ^mpich')
@@ -268,7 +284,7 @@ def database(tmpdir_factory, builtin_mock, config):
                 spack.store.db.remove(spec)
 
     install_path.remove(rec=1)
-    spack.store.root = str(spack_install_path)
+    spack.store.root = spack_install_path
     spack.store.layout = spack_install_layout
     spack.store.db = spack_install_db
 
@@ -285,11 +301,13 @@ def install_mockery(tmpdir, config, builtin_mock):
     """Hooks a fake install directory and a fake db into Spack."""
     layout = spack.store.layout
     db = spack.store.db
+    new_opt = str(tmpdir.join('opt'))
+
     # Use a fake install directory to avoid conflicts bt/w
     # installed pkgs and mock packages.
-    spack.store.layout = spack.directory_layout.YamlDirectoryLayout(
-        str(tmpdir))
-    spack.store.db = spack.database.Database(str(tmpdir))
+    spack.store.layout = spack.directory_layout.YamlDirectoryLayout(new_opt)
+    spack.store.db = spack.database.Database(new_opt)
+
     # We use a fake package, so skip the checksum.
     spack.do_checksum = False
     yield
@@ -328,6 +346,7 @@ def mock_archive():
     """
     tar = spack.util.executable.which('tar', required=True)
     stage = spack.stage.Stage('mock-archive-stage')
+
     tmpdir = py.path.local(stage.path)
     repo_name = 'mock-archive-repo'
     tmpdir.ensure(repo_name, dir=True)
@@ -350,10 +369,10 @@ def mock_archive():
     os.chmod(configure_path, 0o755)
 
     # Archive it
-    current = tmpdir.chdir()
-    archive_name = '{0}.tar.gz'.format(repo_name)
-    tar('-czf', archive_name, repo_name)
-    current.chdir()
+    with tmpdir.as_cwd():
+        archive_name = '{0}.tar.gz'.format(repo_name)
+        tar('-czf', archive_name, repo_name)
+
     Archive = collections.namedtuple('Archive',
                                      ['url', 'path', 'archive_file'])
     archive_file = str(tmpdir.join(archive_name))
@@ -379,46 +398,45 @@ def mock_git_repository():
     repodir = tmpdir.join(repo_name)
 
     # Initialize the repository
-    current = repodir.chdir()
-    git('init')
-    url = 'file://' + str(repodir)
-
-    # r0 is just the first commit
-    r0_file = 'r0_file'
-    repodir.ensure(r0_file)
-    git('add', r0_file)
-    git('commit', '-m', 'mock-git-repo r0')
-
-    branch = 'test-branch'
-    branch_file = 'branch_file'
-    git('branch', branch)
-
-    tag_branch = 'tag-branch'
-    tag_file = 'tag_file'
-    git('branch', tag_branch)
-
-    # Check out first branch
-    git('checkout', branch)
-    repodir.ensure(branch_file)
-    git('add', branch_file)
-    git('commit', '-m' 'r1 test branch')
-
-    # Check out a second branch and tag it
-    git('checkout', tag_branch)
-    repodir.ensure(tag_file)
-    git('add', tag_file)
-    git('commit', '-m' 'tag test branch')
-
-    tag = 'test-tag'
-    git('tag', tag)
-
-    git('checkout', 'master')
-
-    # R1 test is the same as test for branch
-    rev_hash = lambda x: git('rev-parse', x, output=str).strip()
-    r1 = rev_hash(branch)
-    r1_file = branch_file
-    current.chdir()
+    with repodir.as_cwd():
+        git('init')
+        url = 'file://' + str(repodir)
+
+        # r0 is just the first commit
+        r0_file = 'r0_file'
+        repodir.ensure(r0_file)
+        git('add', r0_file)
+        git('commit', '-m', 'mock-git-repo r0')
+
+        branch = 'test-branch'
+        branch_file = 'branch_file'
+        git('branch', branch)
+
+        tag_branch = 'tag-branch'
+        tag_file = 'tag_file'
+        git('branch', tag_branch)
+
+        # Check out first branch
+        git('checkout', branch)
+        repodir.ensure(branch_file)
+        git('add', branch_file)
+        git('commit', '-m' 'r1 test branch')
+
+        # Check out a second branch and tag it
+        git('checkout', tag_branch)
+        repodir.ensure(tag_file)
+        git('add', tag_file)
+        git('commit', '-m' 'tag test branch')
+
+        tag = 'test-tag'
+        git('tag', tag)
+
+        git('checkout', 'master')
+
+        # R1 test is the same as test for branch
+        rev_hash = lambda x: git('rev-parse', x, output=str).strip()
+        r1 = rev_hash(branch)
+        r1_file = branch_file
 
     Bunch = spack.util.pattern.Bunch
 
@@ -457,22 +475,23 @@ def mock_hg_repository():
     get_rev = lambda: hg('id', '-i', output=str).strip()
 
     # Initialize the repository
-    current = repodir.chdir()
-    url = 'file://' + str(repodir)
-    hg('init')
-    # Commit file r0
-    r0_file = 'r0_file'
-    repodir.ensure(r0_file)
-    hg('add', r0_file)
-    hg('commit', '-m', 'revision 0', '-u', 'test')
-    r0 = get_rev()
-    # Commit file r1
-    r1_file = 'r1_file'
-    repodir.ensure(r1_file)
-    hg('add', r1_file)
-    hg('commit', '-m' 'revision 1', '-u', 'test')
-    r1 = get_rev()
-    current.chdir()
+    with repodir.as_cwd():
+        url = 'file://' + str(repodir)
+        hg('init')
+
+        # Commit file r0
+        r0_file = 'r0_file'
+        repodir.ensure(r0_file)
+        hg('add', r0_file)
+        hg('commit', '-m', 'revision 0', '-u', 'test')
+        r0 = get_rev()
+
+        # Commit file r1
+        r1_file = 'r1_file'
+        repodir.ensure(r1_file)
+        hg('add', r1_file)
+        hg('commit', '-m' 'revision 1', '-u', 'test')
+        r1 = get_rev()
 
     Bunch = spack.util.pattern.Bunch
 
@@ -497,64 +516,64 @@ def mock_svn_repository():
     svn = spack.util.executable.which('svn', required=True)
     svnadmin = spack.util.executable.which('svnadmin', required=True)
     stage = spack.stage.Stage('mock-svn-stage')
+
     tmpdir = py.path.local(stage.path)
     repo_name = 'mock-svn-repo'
     tmpdir.ensure(repo_name, dir=True)
     repodir = tmpdir.join(repo_name)
     url = 'file://' + str(repodir)
-    # Initialize the repository
-    current = repodir.chdir()
-    # NOTE: Adding --pre-1.5-compatible works for NERSC
-    # Unknown if this is also an issue at other sites.
-    svnadmin('create', '--pre-1.5-compatible', str(repodir))
-
-    # Import a structure (first commit)
-    r0_file = 'r0_file'
-    tmpdir.ensure('tmp-path', r0_file)
-    svn(
-        'import',
-        str(tmpdir.join('tmp-path')),
-        url,
-        '-m',
-        'Initial import r0'
-    )
-    shutil.rmtree(str(tmpdir.join('tmp-path')))
-    # Second commit
-    r1_file = 'r1_file'
-    svn('checkout', url, str(tmpdir.join('tmp-path')))
-    tmpdir.ensure('tmp-path', r1_file)
-    tmpdir.join('tmp-path').chdir()
-    svn('add', str(tmpdir.ensure('tmp-path', r1_file)))
-    svn('ci', '-m', 'second revision r1')
-    repodir.chdir()
-    shutil.rmtree(str(tmpdir.join('tmp-path')))
-    r0 = '1'
-    r1 = '2'
 
-    Bunch = spack.util.pattern.Bunch
-
-    checks = {
-        'default': Bunch(
-            revision=r1, file=r1_file, args={'svn': url}
-        ),
-        'rev0': Bunch(
-            revision=r0, file=r0_file, args={
-                'svn': url, 'revision': r0
-            }
-        )
-    }
-
-    def get_rev():
-        output = svn('info', output=str)
-        assert "Revision" in output
-        for line in output.split('\n'):
-            match = re.match(r'Revision: (\d+)', line)
-            if match:
-                return match.group(1)
+    # Initialize the repository
+    with repodir.as_cwd():
+        # NOTE: Adding --pre-1.5-compatible works for NERSC
+        # Unknown if this is also an issue at other sites.
+        svnadmin('create', '--pre-1.5-compatible', str(repodir))
+
+        # Import a structure (first commit)
+        r0_file = 'r0_file'
+        tmpdir.ensure('tmp-path', r0_file)
+        tmp_path = tmpdir.join('tmp-path')
+        svn('import',
+            str(tmp_path),
+            url,
+            '-m',
+            'Initial import r0')
+        tmp_path.remove()
+
+        # Second commit
+        r1_file = 'r1_file'
+        svn('checkout', url, str(tmp_path))
+        tmpdir.ensure('tmp-path', r1_file)
+
+        with tmp_path.as_cwd():
+            svn('add', str(tmpdir.ensure('tmp-path', r1_file)))
+            svn('ci', '-m', 'second revision r1')
+
+        tmp_path.remove()
+        r0 = '1'
+        r1 = '2'
+
+        Bunch = spack.util.pattern.Bunch
+
+        checks = {
+            'default': Bunch(
+                revision=r1, file=r1_file, args={'svn': url}),
+            'rev0': Bunch(
+                revision=r0, file=r0_file, args={
+                    'svn': url, 'revision': r0})
+        }
+
+        def get_rev():
+            output = svn('info', output=str)
+            assert "Revision" in output
+            for line in output.split('\n'):
+                match = re.match(r'Revision: (\d+)', line)
+                if match:
+                    return match.group(1)
+
+        t = Bunch(checks=checks, url=url, hash=get_rev, path=str(repodir))
 
-    t = Bunch(checks=checks, url=url, hash=get_rev, path=str(repodir))
     yield t
-    current.chdir()
 
 
 ##########
diff --git a/lib/spack/spack/test/environment.py b/lib/spack/spack/test/environment.py
index 1c787c8e69..6a4d56dc35 100644
--- a/lib/spack/spack/test/environment.py
+++ b/lib/spack/spack/test/environment.py
@@ -47,7 +47,6 @@ def test_inspect_path(tmpdir):
         '': ['CMAKE_PREFIX_PATH']
     }
 
-    tmpdir.chdir()
     tmpdir.mkdir('bin')
     tmpdir.mkdir('lib')
     tmpdir.mkdir('include')
diff --git a/lib/spack/spack/test/git_fetch.py b/lib/spack/spack/test/git_fetch.py
index a23177b946..90b0ae5588 100644
--- a/lib/spack/spack/test/git_fetch.py
+++ b/lib/spack/spack/test/git_fetch.py
@@ -72,22 +72,23 @@ def test_fetch(
         finally:
             spack.insecure = False
 
-        assert h('HEAD') == h(t.revision)
+        with working_dir(pkg.stage.source_path):
+            assert h('HEAD') == h(t.revision)
 
-        file_path = join_path(pkg.stage.source_path, t.file)
-        assert os.path.isdir(pkg.stage.source_path)
-        assert os.path.isfile(file_path)
+            file_path = join_path(pkg.stage.source_path, t.file)
+            assert os.path.isdir(pkg.stage.source_path)
+            assert os.path.isfile(file_path)
 
-        os.unlink(file_path)
-        assert not os.path.isfile(file_path)
+            os.unlink(file_path)
+            assert not os.path.isfile(file_path)
 
-        untracked_file = 'foobarbaz'
-        touch(untracked_file)
-        assert os.path.isfile(untracked_file)
-        pkg.do_restage()
-        assert not os.path.isfile(untracked_file)
+            untracked_file = 'foobarbaz'
+            touch(untracked_file)
+            assert os.path.isfile(untracked_file)
+            pkg.do_restage()
+            assert not os.path.isfile(untracked_file)
 
-        assert os.path.isdir(pkg.stage.source_path)
-        assert os.path.isfile(file_path)
+            assert os.path.isdir(pkg.stage.source_path)
+            assert os.path.isfile(file_path)
 
-        assert h('HEAD') == h(t.revision)
+            assert h('HEAD') == h(t.revision)
diff --git a/lib/spack/spack/test/hg_fetch.py b/lib/spack/spack/test/hg_fetch.py
index 65ec0941d3..410d7a4a42 100644
--- a/lib/spack/spack/test/hg_fetch.py
+++ b/lib/spack/spack/test/hg_fetch.py
@@ -72,22 +72,23 @@ def test_fetch(
         finally:
             spack.insecure = False
 
-        assert h() == t.revision
+        with working_dir(pkg.stage.source_path):
+            assert h() == t.revision
 
-        file_path = join_path(pkg.stage.source_path, t.file)
-        assert os.path.isdir(pkg.stage.source_path)
-        assert os.path.isfile(file_path)
+            file_path = join_path(pkg.stage.source_path, t.file)
+            assert os.path.isdir(pkg.stage.source_path)
+            assert os.path.isfile(file_path)
 
-        os.unlink(file_path)
-        assert not os.path.isfile(file_path)
+            os.unlink(file_path)
+            assert not os.path.isfile(file_path)
 
-        untracked_file = 'foobarbaz'
-        touch(untracked_file)
-        assert os.path.isfile(untracked_file)
-        pkg.do_restage()
-        assert not os.path.isfile(untracked_file)
+            untracked_file = 'foobarbaz'
+            touch(untracked_file)
+            assert os.path.isfile(untracked_file)
+            pkg.do_restage()
+            assert not os.path.isfile(untracked_file)
 
-        assert os.path.isdir(pkg.stage.source_path)
-        assert os.path.isfile(file_path)
+            assert os.path.isdir(pkg.stage.source_path)
+            assert os.path.isfile(file_path)
 
-        assert h() == t.revision
+            assert h() == t.revision
diff --git a/lib/spack/spack/test/mirror.py b/lib/spack/spack/test/mirror.py
index cdaef6dd30..b3929a9844 100644
--- a/lib/spack/spack/test/mirror.py
+++ b/lib/spack/spack/test/mirror.py
@@ -70,11 +70,7 @@ def check_mirror():
         # register mirror with spack config
         mirrors = {'spack-mirror-test': 'file://' + mirror_root}
         spack.config.update_config('mirrors', mirrors)
-
-        os.chdir(stage.path)
-        spack.mirror.create(
-            mirror_root, repos, no_checksum=True
-        )
+        spack.mirror.create(mirror_root, repos, no_checksum=True)
 
         # Stage directory exists
         assert os.path.isdir(mirror_root)
diff --git a/lib/spack/spack/test/packaging.py b/lib/spack/spack/test/packaging.py
index 52e66c99d2..c6029f1575 100644
--- a/lib/spack/spack/test/packaging.py
+++ b/lib/spack/spack/test/packaging.py
@@ -25,20 +25,22 @@
 """
 This test checks the binary packaging infrastructure
 """
+import os
+import stat
+import sys
+import shutil
 import pytest
+import argparse
+
+from llnl.util.filesystem import mkdirp
+
 import spack
 import spack.store
-from spack.fetch_strategy import URLFetchStrategy, FetchStrategyComposite
-from spack.spec import Spec
 import spack.binary_distribution as bindist
-from llnl.util.filesystem import join_path, mkdirp
-import argparse
 import spack.cmd.buildcache as buildcache
+from spack.spec import Spec
+from spack.fetch_strategy import URLFetchStrategy, FetchStrategyComposite
 from spack.relocate import *
-import os
-import stat
-import sys
-import shutil
 from spack.util.executable import ProcessError
 
 
@@ -72,8 +74,8 @@ def test_packaging(mock_archive, tmpdir):
     spec.concretize()
     pkg = spack.repo.get(spec)
     fake_fetchify(pkg.fetcher, pkg)
-    mkdirp(join_path(pkg.prefix, "bin"))
-    patchelfscr = join_path(pkg.prefix, "bin", "patchelf")
+    mkdirp(os.path.join(pkg.prefix, "bin"))
+    patchelfscr = os.path.join(pkg.prefix, "bin", "patchelf")
     f = open(patchelfscr, 'w')
     body = """#!/bin/bash
 echo $PATH"""
@@ -91,14 +93,14 @@ echo $PATH"""
     pkg.do_install()
 
     # Put some non-relocatable file in there
-    filename = join_path(spec.prefix, "dummy.txt")
+    filename = os.path.join(spec.prefix, "dummy.txt")
     with open(filename, "w") as script:
         script.write(spec.prefix)
 
     # Create the build cache  and
     # put it directly into the mirror
 
-    mirror_path = join_path(tmpdir, 'test-mirror')
+    mirror_path = os.path.join(str(tmpdir), 'test-mirror')
     specs = [spec]
     spack.mirror.create(
         mirror_path, specs, no_checksum=True
@@ -286,18 +288,25 @@ def test_relocate():
 
 @pytest.mark.skipif(sys.platform != 'darwin',
                     reason="only works with Mach-o objects")
-def test_relocate_macho():
-    get_patchelf()
-    assert (needs_binary_relocation('Mach-O') is True)
-    macho_get_paths('/bin/bash')
-    shutil.copyfile('/bin/bash', 'bash')
-    modify_macho_object('bash', '/bin/bash', '/usr', '/opt', False)
-    modify_macho_object('bash', '/bin/bash', '/usr', '/opt', True)
-    shutil.copyfile('/usr/lib/libncurses.5.4.dylib', 'libncurses.5.4.dylib')
-    modify_macho_object('libncurses.5.4.dylib',
-                        '/usr/lib/libncurses.5.4.dylib', '/usr', '/opt', False)
-    modify_macho_object('libncurses.5.4.dylib',
-                        '/usr/lib/libncurses.5.4.dylib', '/usr', '/opt', True)
+def test_relocate_macho(tmpdir):
+    with tmpdir.as_cwd():
+        get_patchelf()
+        assert (needs_binary_relocation('Mach-O') is True)
+
+        macho_get_paths('/bin/bash')
+        shutil.copyfile('/bin/bash', 'bash')
+
+        modify_macho_object('bash', '/bin/bash', '/usr', '/opt', False)
+        modify_macho_object('bash', '/bin/bash', '/usr', '/opt', True)
+
+        shutil.copyfile(
+            '/usr/lib/libncurses.5.4.dylib', 'libncurses.5.4.dylib')
+        modify_macho_object(
+            'libncurses.5.4.dylib',
+            '/usr/lib/libncurses.5.4.dylib', '/usr', '/opt', False)
+        modify_macho_object(
+            'libncurses.5.4.dylib',
+            '/usr/lib/libncurses.5.4.dylib', '/usr', '/opt', True)
 
 
 @pytest.mark.skipif(sys.platform != 'linux2',
diff --git a/lib/spack/spack/test/stage.py b/lib/spack/spack/test/stage.py
index d6d2eeb506..ffd2ed5afb 100644
--- a/lib/spack/spack/test/stage.py
+++ b/lib/spack/spack/test/stage.py
@@ -30,18 +30,10 @@ import pytest
 import spack
 import spack.stage
 import spack.util.executable
-from llnl.util.filesystem import join_path
+from llnl.util.filesystem import join_path, working_dir
 from spack.stage import Stage
 
 
-def check_chdir_to_source(stage, stage_name):
-    stage_path = get_stage_path(stage, stage_name)
-    archive_dir = 'test-files'
-    assert join_path(
-        os.path.realpath(stage_path), archive_dir
-    ) == os.getcwd()
-
-
 def check_expand_archive(stage, stage_name, mock_archive):
     stage_path = get_stage_path(stage, stage_name)
     archive_name = 'test-files.tar.gz'
@@ -64,11 +56,6 @@ def check_fetch(stage, stage_name):
     assert join_path(stage_path, archive_name) == stage.fetcher.archive_file
 
 
-def check_chdir(stage, stage_name):
-    stage_path = get_stage_path(stage, stage_name)
-    assert os.path.realpath(stage_path) == os.getcwd()
-
-
 def check_destroy(stage, stage_name):
     """Figure out whether a stage was destroyed correctly."""
     stage_path = get_stage_path(stage, stage_name)
@@ -162,10 +149,9 @@ def mock_archive(tmpdir, monkeypatch):
     test_tmp_path.ensure(dir=True)
     test_readme.write('hello world!\n')
 
-    current = tmpdir.chdir()
-    tar = spack.util.executable.which('tar', required=True)
-    tar('czf', str(archive_name), 'test-files')
-    current.chdir()
+    with tmpdir.as_cwd():
+        tar = spack.util.executable.which('tar', required=True)
+        tar('czf', str(archive_name), 'test-files')
 
     # Make spack use the test environment for tmp stuff.
     monkeypatch.setattr(spack.stage, '_tmp_root', None)
@@ -180,9 +166,6 @@ def mock_archive(tmpdir, monkeypatch):
         test_tmp_dir=test_tmp_path,
         archive_dir=archive_dir
     )
-    # record this since this test changes to directories that will
-    # be removed.
-    current.chdir()
 
 
 @pytest.fixture()
@@ -245,18 +228,10 @@ class TestStage(object):
             check_setup(stage, None, mock_archive)
         check_destroy(stage, None)
 
-    def test_chdir(self, mock_archive):
-        with Stage(mock_archive.url, name=self.stage_name) as stage:
-            stage.chdir()
-            check_setup(stage, self.stage_name, mock_archive)
-            check_chdir(stage, self.stage_name)
-        check_destroy(stage, self.stage_name)
-
     def test_fetch(self, mock_archive):
         with Stage(mock_archive.url, name=self.stage_name) as stage:
             stage.fetch()
             check_setup(stage, self.stage_name, mock_archive)
-            check_chdir(stage, self.stage_name)
             check_fetch(stage, self.stage_name)
         check_destroy(stage, self.stage_name)
 
@@ -307,37 +282,23 @@ class TestStage(object):
             check_expand_archive(stage, self.stage_name, mock_archive)
         check_destroy(stage, self.stage_name)
 
-    def test_expand_archive_with_chdir(self, mock_archive):
-        with Stage(mock_archive.url, name=self.stage_name) as stage:
-            stage.fetch()
-            check_setup(stage, self.stage_name, mock_archive)
-            check_fetch(stage, self.stage_name)
-            stage.expand_archive()
-            stage.chdir_to_source()
-            check_expand_archive(stage, self.stage_name, mock_archive)
-            check_chdir_to_source(stage, self.stage_name)
-        check_destroy(stage, self.stage_name)
-
     def test_restage(self, mock_archive):
         with Stage(mock_archive.url, name=self.stage_name) as stage:
             stage.fetch()
             stage.expand_archive()
-            stage.chdir_to_source()
-            check_expand_archive(stage, self.stage_name, mock_archive)
-            check_chdir_to_source(stage, self.stage_name)
 
-            # Try to make a file in the old archive dir
-            with open('foobar', 'w') as file:
-                file.write("this file is to be destroyed.")
+            with working_dir(stage.source_path):
+                check_expand_archive(stage, self.stage_name, mock_archive)
+
+                # Try to make a file in the old archive dir
+                with open('foobar', 'w') as file:
+                    file.write("this file is to be destroyed.")
 
             assert 'foobar' in os.listdir(stage.source_path)
 
             # Make sure the file is not there after restage.
             stage.restage()
-            check_chdir(stage, self.stage_name)
             check_fetch(stage, self.stage_name)
-            stage.chdir_to_source()
-            check_chdir_to_source(stage, self.stage_name)
             assert 'foobar' not in os.listdir(stage.source_path)
         check_destroy(stage, self.stage_name)
 
diff --git a/lib/spack/spack/test/svn_fetch.py b/lib/spack/spack/test/svn_fetch.py
index 2b13d2b4f1..304edc2828 100644
--- a/lib/spack/spack/test/svn_fetch.py
+++ b/lib/spack/spack/test/svn_fetch.py
@@ -72,22 +72,23 @@ def test_fetch(
         finally:
             spack.insecure = False
 
-        assert h() == t.revision
+        with working_dir(pkg.stage.source_path):
+            assert h() == t.revision
 
-        file_path = join_path(pkg.stage.source_path, t.file)
-        assert os.path.isdir(pkg.stage.source_path)
-        assert os.path.isfile(file_path)
+            file_path = join_path(pkg.stage.source_path, t.file)
+            assert os.path.isdir(pkg.stage.source_path)
+            assert os.path.isfile(file_path)
 
-        os.unlink(file_path)
-        assert not os.path.isfile(file_path)
+            os.unlink(file_path)
+            assert not os.path.isfile(file_path)
 
-        untracked_file = 'foobarbaz'
-        touch(untracked_file)
-        assert os.path.isfile(untracked_file)
-        pkg.do_restage()
-        assert not os.path.isfile(untracked_file)
+            untracked_file = 'foobarbaz'
+            touch(untracked_file)
+            assert os.path.isfile(untracked_file)
+            pkg.do_restage()
+            assert not os.path.isfile(untracked_file)
 
-        assert os.path.isdir(pkg.stage.source_path)
-        assert os.path.isfile(file_path)
+            assert os.path.isdir(pkg.stage.source_path)
+            assert os.path.isfile(file_path)
 
-        assert h() == t.revision
+            assert h() == t.revision
diff --git a/lib/spack/spack/test/url_fetch.py b/lib/spack/spack/test/url_fetch.py
index c51037a254..21d871173e 100644
--- a/lib/spack/spack/test/url_fetch.py
+++ b/lib/spack/spack/test/url_fetch.py
@@ -72,13 +72,14 @@ def test_fetch(
         finally:
             spack.insecure = False
 
-        assert os.path.exists('configure')
-        assert is_exe('configure')
-
-        with open('configure') as f:
-            contents = f.read()
-        assert contents.startswith('#!/bin/sh')
-        assert 'echo Building...' in contents
+        with working_dir(pkg.stage.source_path):
+            assert os.path.exists('configure')
+            assert is_exe('configure')
+
+            with open('configure') as f:
+                contents = f.read()
+            assert contents.startswith('#!/bin/sh')
+            assert 'echo Building...' in contents
 
 
 def test_hash_detection(checksum_type):