Added a rudimentary test framework

Tests can be found in 'tests/test_blah.sh'
Tests can be run with 'make test'

tests/test_format.sh

@@ -0,0 +1,45 @@
+#!/bin/bash
+set -eu
+
+echo "=== Formatting tests ==="
+rm -rf blocks
+
+echo "--- Basic formatting ---"
+./tests/test.py << TEST
+    lfs_format(&lfs, &bd, &lfs_emubd_ops) => 0;
+TEST
+
+echo "--- Invalid superblocks ---"
+ln -f -s /dev/null blocks/0
+./tests/test.py << TEST
+    lfs_format(&lfs, &bd, &lfs_emubd_ops) => LFS_ERROR_CORRUPT;
+TEST
+rm blocks/0
+
+echo "--- Basic mounting ---"
+./tests/test.py << TEST
+    lfs_mount(&lfs, &bd, &lfs_emubd_ops) => 0;
+    lfs_unmount(&lfs) => 0;
+TEST
+
+echo "--- Invalid mount ---"
+./tests/test.py << TEST
+    lfs_format(&lfs, &bd, &lfs_emubd_ops) => 0;
+TEST
+rm blocks/0 blocks/1
+./tests/test.py << TEST
+    lfs_mount(&lfs, &bd, &lfs_emubd_ops) => LFS_ERROR_CORRUPT;
+TEST
+
+echo "--- Valid corrupt mount ---"
+./tests/test.py << TEST
+    lfs_format(&lfs, &bd, &lfs_emubd_ops) => 0;
+TEST
+rm blocks/0
+./tests/test.py << TEST
+    lfs_mount(&lfs, &bd, &lfs_emubd_ops) => 0;
+    lfs_unmount(&lfs) => 0;
+TEST
+
+echo "--- Results ---"
+./tests/stats.py