Fix shellcheck warnings, test in CI

.buildkite/pipeline.yml

@@ -1,3 +1,3 @@
 steps:
-  - label: ":partyparrot:"
-    command: git log -1
+  - label: ":bash: shellcheck"
+    command: shellcheck *.sh

post-receive.sh

@@ -1,8 +1,6 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
-# TODO: Check compatability with config file
-
 REPO=$(pwd)
 CONFIG="$HOME/.mandarin-duck/mandarin-duck.cfg"
 CONFIG_VERSION=$(jq --raw-output ".version // \"\"" "$CONFIG")
@@ -11,29 +9,29 @@ if [[ $CONFIG_VERSION != 1.* ]]; then
     exit 1
 fi
 BUILDKITE_API_TOKEN=$(jq --raw-output ".buildkite_api_token // \"\"" "$CONFIG")
-if [[ $BUILDKITE_API_TOKEN == '' ]]; then
+if [[ $BUILDKITE_API_TOKEN == "" ]]; then
     echo -e "\033[31mBuildkite API token not set, check your config at $CONFIG\033[0m"
     exit 1
 fi
 BUILDKITE_ORGANIZATION_SLUG=$(jq --raw-output ".buildkite_organization_slug // \"\"" "$CONFIG")
-if [[ $BUILDKITE_ORGANIZATION_SLUG == '' ]]; then
+if [[ $BUILDKITE_ORGANIZATION_SLUG == "" ]]; then
     echo -e "\033[31mBuildkite organization name not set, check your config at $CONFIG\033[0m"
     exit 1
 fi
 BUILDKITE_PIPELINE_SLUG=$(jq --raw-output ".projects[\"$REPO\"].buildkite_pipeline_slug // \"\"" "$CONFIG")
-if [[ $BUILDKITE_PIPELINE_SLUG == '' ]]; then
+if [[ $BUILDKITE_PIPELINE_SLUG == "" ]]; then
     echo -e "\033[31mBuildkite pipeline name not set, check your config at $CONFIG\033[0m"
     exit 1
 fi
 
 # Hacky way of getting all branch names from list of updated local refs
-cut -d ' ' -f 3 | sort | uniq | grep "refs/heads/" | cut -c 12- | while read BRANCH; do
+cut -d " " -f 3 | sort | uniq | grep "refs/heads/" | cut -c 12- | while read -r BRANCH; do
     echo -e "--- Triggering Buildkite build on \033[32m$BRANCH\033[0m"
     echo -n "You can view this build at "
-    curl --fail --silent -X POST https://api.buildkite.com/v2/organizations/$BUILDKITE_ORGANIZATION_SLUG/pipelines/$BUILDKITE_PIPELINE_SLUG/builds \
+    curl --fail --silent -X POST "https://api.buildkite.com/v2/organizations/$BUILDKITE_ORGANIZATION_SLUG/pipelines/$BUILDKITE_PIPELINE_SLUG/builds" \
         -H "Authorization: Bearer $BUILDKITE_API_TOKEN" \
         -d "{
             \"commit\": \"HEAD\",
             \"branch\": \"$BRANCH\"
-        }" | jq --raw-output '.web_url'
+        }" | jq --raw-output ".web_url"
 done