Empty the default KERNELS map and make tests chroot-safe

Custom kernels are now set only in the config, so the defaults suit any system. The reboot check's modules folder can be overridden with UPDATE_NOTIFY_MODULES_DIR, so the tests no longer need an installed kernel.

tests/update-notify.bats

@@ -7,27 +7,17 @@ bats_load_library bats-assert
 
 SCRIPT=$BATS_TEST_DIRNAME/../update-notify
 
-setup_file() {
-    # A kernel release whose vmlinuz exists, so the reboot check stays quiet unless a test fakes one
-    local f
-    for f in /usr/lib/modules/*/vmlinuz; do
-        [[ -e $f ]] || continue
-        f=${f%/vmlinuz}
-        export INSTALLED_KERNEL=${f##*/}
-        return
-    done
-    echo "no /usr/lib/modules/*/vmlinuz found" >&2
-    return 1
-}
-
 setup() {
     export STUB_DATA=$BATS_TEST_TMPDIR/data
     export XDG_CONFIG_HOME=$BATS_TEST_TMPDIR/config
     export XDG_STATE_HOME=$BATS_TEST_TMPDIR/state
-    export STUB_KERNEL=$INSTALLED_KERNEL
+    # The running kernel has its vmlinuz, so the reboot check stays quiet unless a test changes STUB_KERNEL
+    export STUB_KERNEL=6.1.1-test
+    export UPDATE_NOTIFY_MODULES_DIR=$BATS_TEST_TMPDIR/modules
     STATE=$XDG_STATE_HOME/update-notify
     BIN=$BATS_TEST_TMPDIR/bin
-    mkdir -p "$STUB_DATA" "$XDG_CONFIG_HOME/update-notify" "$BIN"
+    mkdir -p "$STUB_DATA" "$XDG_CONFIG_HOME/update-notify" "$BIN" "$UPDATE_NOTIFY_MODULES_DIR/$STUB_KERNEL"
+    touch "$UPDATE_NOTIFY_MODULES_DIR/$STUB_KERNEL/vmlinuz"
     # PATH holds only the stubs and the real tools the script needs, so a removed stub is a missing command
     local tool
     for tool in mkdir mv rm id timeout vercmp; do
@@ -45,6 +35,7 @@ repo_updates() { printf '%s\n' "$@" > "$STUB_DATA/checkupdates"; }
 aur_updates() { printf '%s\n' "$@" > "$STUB_DATA/aur"; }
 installed() { printf '%s\n' "$@" > "$STUB_DATA/installed"; }
 pacnew_files() { printf '%s\n' "$@" > "$STUB_DATA/pacdiff"; }
+custom_linux() { config "KERNELS=([linux]=linux-custom)"; }
 
 # Runs the script; notifications and stub calls are logged from this run only
 run_script() {
@@ -178,7 +169,17 @@ assert_called() {
 
 # --- Kernel check ---
 
+@test "no kernel check by default" {
+    installed "linux 6.1.1-1" "linux-custom 6.1.1-1"
+    repo_updates "linux 6.1.1-1 -> 6.1.2-1"
+    run_script
+    assert_success
+    assert_no_notification
+    assert_pending "threshold 30" "repo linux 6.1.2-1"
+}
+
 @test "stock kernel update notifies the rebuild below the threshold" {
+    custom_linux
     installed "linux 6.1.1-1" "linux-custom 6.1.1-1"
     repo_updates "linux 6.1.1-1 -> 6.1.2-1"
     run_script
@@ -189,6 +190,7 @@ assert_called() {
 
 @test "kernel rebuild joins the counts over the threshold" {
     config THRESHOLD=1
+    custom_linux
     installed "linux 6.1.2-1" "linux-custom 6.1.1-1"
     run_script 0
     assert_success
@@ -196,6 +198,7 @@ assert_called() {
 }
 
 @test "kernel check ignores pkgrel" {
+    custom_linux
     installed "linux 6.1.1-1" "linux-custom 6.1.1-1"
     repo_updates "linux 6.1.1-1 -> 6.1.1-2"
     run_script
@@ -204,6 +207,7 @@ assert_called() {
 }
 
 @test "custom kernel already built into the repo isn't flagged" {
+    custom_linux
     installed "linux 6.1.1-1" "linux-custom 6.1.1-1"
     repo_updates "linux 6.1.1-1 -> 6.1.2-1" "linux-custom 6.1.1-1 -> 6.1.2-1"
     run_script
@@ -212,6 +216,7 @@ assert_called() {
 }
 
 @test "kernels without a custom build installed are skipped" {
+    custom_linux
     installed "linux 6.1.1-1"
     repo_updates "linux 6.1.1-1 -> 6.1.2-1"
     run_script
@@ -221,8 +226,7 @@ assert_called() {
 
 @test "custom kernel map comes from the config" {
     config "KERNELS=([linux-hardened]=linux-hardened-mine)"
-    installed "linux 6.1.1-1" "linux-custom 6.1.1-1" "linux-hardened 6.1.2-1" "linux-hardened-mine 6.1.1-1"
-    repo_updates "linux 6.1.1-1 -> 6.1.2-1"
+    installed "linux-hardened 6.1.2-1" "linux-hardened-mine 6.1.1-1"
     run_script
     assert_success
     assert_notification "Kernel update available" "Rebuild linux-hardened-mine (linux-hardened 6.1.2-1)"
@@ -398,6 +402,7 @@ assert_called() {
 @test "no reminders below the threshold" {
     enable_stub git-monitor
     enable_stub fwupdmgr
+    custom_linux
     installed "linux 6.1.2-1" "linux-custom 6.1.1-1"
     run_script
     assert_notification "Kernel update available" "Rebuild linux-custom (linux 6.1.2-1)"