tests: ensure snapd can be downloaded as a module (#11052)

LP#1948838: moved files that cause an issue during git module download to tar files in the corresponding folders

Add spread test for validating snaps can be packed and installed (as well as `snap try`'d) with various circular symlinks.

spread.yaml

@@ -785,7 +785,7 @@ suites:
             _/hosts: _
             _/hosts_n_dirs: _
             # twisted fails in travis (but not regular spread).
-            # _/twisted: _
+            #_/twisted: _
             _/func: _
             _/funkyfunc: _
             _/funcarg: _

tests/completion/twisted.sh

@@ -1 +1,2 @@
 cd "$SPREAD_PATH/$SPREAD_SUITE/data/twisted"
+tar -xvf $SPREAD_PATH/$SPREAD_SUITE/data/twisted/twisted.tar

tests/main/validate-container-happy/task.yaml

@@ -0,0 +1,38 @@
+summary: check the symlinks following the right track
+
+environment:
+    SNAP: test-snapd-validate-container-happy
+
+prepare: |
+
+execute: |
+
+    SNAP_MOUNT_DIR="$(os.paths snap-mount-dir)"
+
+    # We shouldn't use relative symlinks in Github as they cannot be packed correctly.
+    # So here let's test whether we can still pack such symlinks within a snap and use if needed.
+    # First we "try" to unpack the snap structure and untar the symlinks
+    # Then we pack the snap with these symlinks and then install
+    # Finally we check to see if the symlinks actually support the intervined symlinks
+
+    # Untar the symlinks 
+    tar -xvf "$SNAP"/hell/hell.tar -C "$SNAP"/hell
+
+    snap try "$SNAP"
+    # Check to see if the symlinks point to the right paths
+    readlink "$SNAP_MOUNT_DIR"/"$SNAP"/current/hell/bar | MATCH "foo -> baz -> qux"
+    readlink "$SNAP_MOUNT_DIR"/"$SNAP"/current/hell/baz | MATCH "foo -> bar -> qux"
+    readlink "$SNAP_MOUNT_DIR"/"$SNAP"/current/hell/foo | MATCH "bar -> baz -> qux"
+    readlink "$SNAP_MOUNT_DIR"/"$SNAP"/current/hell/qux | MATCH "foo -> bar -> baz"
+    snap remove "$SNAP"
+
+    # Create a new snap structure that includes the unpacked symlinks
+    snap pack "$SNAP"
+    snap install --dangerous test-snapd-validate-container-happy_1.0_all.snap
+    tests.cleanup defer snap remove --purge test-snapd-validate-container-happy
+
+    # Check to see if the symlinks retain their existing paths
+    readlink "$SNAP_MOUNT_DIR"/"$SNAP"/current/hell/bar | MATCH "foo -> baz -> qux"
+    readlink "$SNAP_MOUNT_DIR"/"$SNAP"/current/hell/baz | MATCH "foo -> bar -> qux"
+    readlink "$SNAP_MOUNT_DIR"/"$SNAP"/current/hell/foo | MATCH "bar -> baz -> qux"
+    readlink "$SNAP_MOUNT_DIR"/"$SNAP"/current/hell/qux | MATCH "foo -> bar -> baz"

tests/main/validate-container-happy/test-snapd-validate-container-happy/meta/snap.yaml

@@ -0,0 +1,5 @@
+name: test-snapd-validate-container-happy
+version: 1.0
+apps:
+  validate-container:
+    command: bin/validate-container