Merge branch 'liw/yarn-snapshots'

3 files changed, 129 insertions, 2 deletions

diff --git a/NEWS b/NEWS
index c948376..f7d4f4f 100644
--- a/NEWS
+++ b/NEWS
@@ -12,6 +12,9 @@ Version 0.X, released UNRELEASED
 * FINALLY always worked in yarn, but has now been added to the manual
   page as well.
 * New yarn option `--run` allows running selected tests only.
+* New yarn option `--snapshot` makes snapshots of the test working
+  directory after each step in a scenario. Combined with the, also
+  new, option `--tempdir` this makes debugging failed tests easier.
 
 Bug fixes:
 
diff --git a/yarn b/yarn
index e3ed242..c25a929 100755
--- a/yarn
+++ b/yarn
@@ -50,6 +50,18 @@ class YarnRunner(cliapp.Application):
             'run only TEST (this option can be repeated)',
             metavar='TEST')
 
+        self.settings.string(
+            ['tempdir'],
+            'use DIR as the temporary directory for tests; '
+                'it should be empty or not exist',
+            metavar='DIR')
+
+        self.settings.boolean(
+            ['snapshot'],
+            'make snapshots of test working directory '
+                'after each scenario step; you probably '
+                'want to use this with --tempdir')
+
     def setup(self):
         self.ts = ttystatus.TerminalStatus(period=0.001)
         if not self.settings['quiet']:
@@ -170,26 +182,43 @@ class YarnRunner(cliapp.Application):
         if self.settings['no-act']:
             return True
 
-        datadir = tempfile.mkdtemp()
+        if self.settings['tempdir']:
+            tempdir = self.settings['tempdir']
+            if not os.path.exists(tempdir):
+                os.mkdir(tempdir)
+        else:
+            tempdir = tempfile.mkdtemp()
+
+        os.mkdir(self.scenario_dir(tempdir, scenario))
+        datadir = self.datadir(tempdir, scenario)
+        os.mkdir(datadir)
 
         cleanup = [s for s in scenario.steps if s.what == 'FINALLY']
         normal = [s for s in scenario.steps if s not in cleanup]
 
         ok = True
+        step_number = 0
 
         for step in normal:
             exit = self.run_step(datadir, scenario, step, shell_prelude)
+            step_number += 1
+            self.snapshot_datadir(
+                tempdir, datadir, scenario, step_number, step)
             if exit != 0:
                 ok = False
                 break
 
         for step in cleanup:
             exit = self.run_step(datadir, scenario, step, shell_prelude)
+            step_number += 1
+            self.snapshot_datadir(
+                tempdir, datadir, scenario, step_number, step)
             if exit != 0:
                 ok = False
                 break
 
-        shutil.rmtree(datadir)
+        if not self.settings['snapshot']:
+            shutil.rmtree(tempdir)
 
         return ok
 
@@ -232,6 +261,39 @@ class YarnRunner(cliapp.Application):
 
         return exit
 
+    def scenario_dir(self, tempdir, scenario):
+        return os.path.join(tempdir, self.nice(scenario.name))
+
+    def datadir(self, tempdir, scenario):
+        sd = self.scenario_dir(tempdir, scenario)
+        return os.path.join(sd, 'datadir')
+
+    def snapshot_dir(self, tempdir, scenario, step, step_number):
+        sd = self.scenario_dir(tempdir, scenario)
+        base = '%03d-%s-%s' % (step_number, step.what, self.nice(step.text))
+        return os.path.join(sd, base)
+
+    def snapshot_datadir(self, tempdir, datadir, scenario, step_number, step):
+        # Use --reflink in case of CoW support, e.g., btrfs.
+        snapshot = self.snapshot_dir(tempdir, scenario, step, step_number)
+        cliapp.runcmd(
+            ['cp', '-a', '--reflink=auto', datadir, snapshot])
+
+    def nice(self, name):
+        # Quote a scenario or step name so it forms a nice filename.
+        nice_chars = "abcdefghijklmnopqrstuvwxyz"
+        nice_chars += nice_chars.upper()
+        nice_chars += "0123456789-."
+
+        nice = []
+        for c in name:
+            if c in nice_chars:
+                nice.append(c)
+            elif not nice or nice[-1] != '_':
+                nice.append('_')
+        nice = ''.join(nice)
+        return nice
+
     def indent(self, s):
         return ''.join('    %s\n' % line for line in s.splitlines())
 
diff --git a/yarn.tests/snapshot.script b/yarn.tests/snapshot.script
new file mode 100755
index 0000000..e8947ad
--- /dev/null
+++ b/yarn.tests/snapshot.script
@@ -0,0 +1,62 @@
+#!/bin/sh
+
+set -eu
+
+cat << EOF > "$DATADIR/foo.yarn"
+    SCENARIO foo
+    GIVEN foo
+    WHEN foo
+    THEN foo
+
+    SCENARIO bar
+    GIVEN bar
+    WHEN bar
+    THEN bar
+
+    IMPLEMENTS GIVEN (.*)
+    touch "\$DATADIR/\$MATCH_1.given"
+
+    IMPLEMENTS WHEN (.*)
+    touch "\$DATADIR/\$MATCH_1.when"
+
+    IMPLEMENTS THEN (.*)
+    touch "\$DATADIR/\$MATCH_1.then"
+EOF
+
+./yarn -q --snapshot --tempdir "$DATADIR/tmp" "$DATADIR/foo.yarn"
+
+test -e "$DATADIR/tmp/bar"
+test -e "$DATADIR/tmp/bar/datadir"
+test -e "$DATADIR/tmp/bar/datadir/bar.given"
+test -e "$DATADIR/tmp/bar/datadir/bar.when"
+test -e "$DATADIR/tmp/bar/datadir/bar.then"
+
+test -e "$DATADIR/tmp/bar/001-GIVEN-bar"
+test -e "$DATADIR/tmp/bar/001-GIVEN-bar/bar.given"
+! test -e "$DATADIR/tmp/bar/001-GIVEN-bar/bar.when"
+! test -e "$DATADIR/tmp/bar/001-GIVEN-bar/bar.then"
+
+test -e "$DATADIR/tmp/bar/002-WHEN-bar"
+test -e "$DATADIR/tmp/bar/002-WHEN-bar/bar.given"
+test -e "$DATADIR/tmp/bar/002-WHEN-bar/bar.when"
+! test -e "$DATADIR/tmp/bar/002-WHEN-bar/bar.then"
+
+test -e "$DATADIR/tmp/bar/003-THEN-bar"
+test -e "$DATADIR/tmp/bar/003-THEN-bar/bar.given"
+test -e "$DATADIR/tmp/bar/003-THEN-bar/bar.when"
+test -e "$DATADIR/tmp/bar/003-THEN-bar/bar.then"
+
+test -e "$DATADIR/tmp/foo/001-GIVEN-foo"
+test -e "$DATADIR/tmp/foo/001-GIVEN-foo/foo.given"
+! test -e "$DATADIR/tmp/foo/001-GIVEN-foo/foo.when"
+! test -e "$DATADIR/tmp/foo/001-GIVEN-foo/foo.then"
+
+test -e "$DATADIR/tmp/foo/002-WHEN-foo"
+test -e "$DATADIR/tmp/foo/002-WHEN-foo/foo.given"
+test -e "$DATADIR/tmp/foo/002-WHEN-foo/foo.when"
+! test -e "$DATADIR/tmp/foo/002-WHEN-foo/foo.then"
+
+test -e "$DATADIR/tmp/foo/003-THEN-foo"
+test -e "$DATADIR/tmp/foo/003-THEN-foo/foo.given"
+test -e "$DATADIR/tmp/foo/003-THEN-foo/foo.when"
+test -e "$DATADIR/tmp/foo/003-THEN-foo/foo.then"