test: add tests for python bindings

We start modestly, with a (slightly modified) test case from Kazuo
Teramoto. Originally it just made sure the bindings didn't crash; here
we check that by comparing the output with that of notmuch search.

test/notmuch-test

@@ -47,6 +47,7 @@ TESTS="
   symbol-hiding
   search-folder-coherence
   atomicity
+  python
 "
 TESTS=${NOTMUCH_TESTS:=$TESTS}
 

test/python

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+test_description="python bindings"
+. ./test-lib.sh
+
+add_email_corpus
+
+test_begin_subtest "compare thread ids"
+python <<EOF | sort > OUTPUT
+import notmuch
+db = notmuch.Database(mode=notmuch.Database.MODE.READ_WRITE)
+q_new = notmuch.Query(db, 'tag:inbox')
+for t in q_new.search_threads():
+    print t.get_thread_id()
+EOF
+notmuch search --output=threads tag:inbox | sed s/^thread:// | sort > EXPECTED
+test_expect_equal_file OUTPUT EXPECTED
+test_done