t/main/snap-tasks: create spread test to ensure --format json produces valid JSON

Author: Rnfudge02

tests/main/snap-tasks/tasks.yaml

@@ -0,0 +1,26 @@
+summary: Check that `snap tasks` works as expected.
+
+details: |
+  Verifies that the command `snap tasks` properly lists the tasks
+  associated with a change. Also check the error scenarios.
+
+systems: [ubuntu-16.04-64, ubuntu-18.04-64, ubuntu-2*, ubuntu-core-*, fedora-*]
+
+prepare: |
+  # Install local test snap
+  "$TESTSTOOLS"/install-local test-snap-with-components
+
+restore: |
+  snap remove --purge test-snap-tasks || true
+
+execute: |
+  echo "Install component to trigger a change"
+  snap install test-snap-with-components+comp1
+
+  echo "Get the change ID for the install operation"
+  CHANGE_ID_1=$(snap changes | grep "Install snap \"test-snap-with-components\"" | awk '{print $1}')
+
+  # Check that valid JSON output is produced for the change, and that it contains the expected task with the expected state.
+  echo "Check that 'snap tasks' lists the task for the change (and accepts the --format option)"
+  snap tasks --format json "$CHANGE_ID_1" | jq -e '.[0].id == "remove+comp1" and .[0].state == "done"' > /dev/null
+