tmt: Add bootc-image-builder integration test for issue #1907

Add a TMT test that exercises the mount point check fix from PR #1904.
The test builds a container image with an embedded disk.yaml that creates
a partition layout WITHOUT a separate /boot partition - just root (/)
with /boot/efi as a separate mount point.

This partition layout triggers the bug from issue #1907 where bootc's
empty rootfs verification would fail with:
  "Found entry in boot: efi"

The issue was that when /boot is a directory on the root filesystem
(not a separate partition), but /boot/efi IS a mount point on a different
device, the old code incorrectly saw "efi" as a regular directory entry
rather than recognizing it was a mount point boundary.

Verified that temporarily reverting the fix from PR #1904 causes this
test to fail with the expected error message.

This was already fixed by ab65078675
but we didn't realize at the time the scope.

Closes: https://github.com/bootc-dev/bootc/issues/1907
Signed-off-by: Colin Walters <walters@verbum.org>

tmt/plans/integration.fmf

@@ -159,4 +159,11 @@ execute:
     how: fmf
     test:
       - /tmt/tests/tests/test-32-install-to-filesystem-var-mount
+
+/plan-33-bib-build:
+  summary: Test building a qcow2 disk image with bootc-image-builder
+  discover:
+    how: fmf
+    test:
+      - /tmt/tests/tests/test-33-bib-build
 # END GENERATED PLANS

tmt/tests/booted/test-bib-build.nu

@@ -0,0 +1,120 @@
+# number: 33
+# tmt:
+#   summary: Test building a qcow2 disk image with bootc-image-builder
+#   duration: 45m
+#   require:
+#     - qemu-img
+#
+# This test validates that bootc-image-builder (bib) can successfully
+# create disk images from the current booted image. This is a critical
+# integration test to catch regressions like:
+# https://github.com/bootc-dev/bootc/issues/1907
+#
+# The key scenario tested here is a partition layout where /boot is a
+# directory on the root filesystem (NOT a separate partition), but
+# /boot/efi IS a separate mount point. The bug was that when bootc
+# checked /boot, it found "efi" as a directory entry and failed to
+# recognize it was actually a mount point on a different device.
+#
+use std assert
+use tap.nu
+
+const BIB_IMAGE = "quay.io/centos-bootc/bootc-image-builder:latest"
+
+def main [] {
+    tap begin "bootc-image-builder qcow2 build test"
+
+    let td = mktemp -d
+    cd $td
+
+    # Copy the currently booted image to podman storage
+    print "=== Copying booted image to containers-storage ==="
+    bootc image copy-to-storage
+    
+    # Verify the image is in storage
+    let images = podman images --format json | from json
+    let bootc_img = $images | where Names != null | where { |img| 
+        $img.Names | any { |t| $t == "localhost/bootc:latest" }
+    }
+    assert (($bootc_img | length) > 0) "Expected localhost/bootc image in podman storage"
+
+    # Build a derived image that:
+    # 1. Removes bound images (bib runs isolated)
+    # 2. Embeds a disk.yaml that creates a layout WITHOUT a separate /boot partition
+    #    This triggers the bug from issue #1907 where /boot is a directory on root
+    #    and /boot/efi is a mount point
+    print "=== Building derived image with no-/boot-partition layout ==="
+    'FROM localhost/bootc
+RUN rm -rf /usr/lib/bootc/bound-images.d/*
+RUN mkdir -p /usr/lib/bootc-image-builder && cat > /usr/lib/bootc-image-builder/disk.yaml << "DISKEOF"
+# Partition layout without a separate /boot partition.
+# This mimics the CentOS Automotive ukiboot layout and triggers issue #1907.
+# The key is that /boot is a directory on root, but /boot/efi is a mount point.
+.common:
+  partitioning:
+    guids:
+      - &bios_boot_partition_guid "21686148-6449-6E6F-744E-656564454649"
+      - &efi_system_partition_guid "C12A7328-F81F-11D2-BA4B-00A0C93EC93B"
+      - &filesystem_data_guid "0FC63DAF-8483-4772-8E79-3D69D8477DE4"
+
+partition_table:
+  type: "gpt"
+  partitions:
+    - size: "1 MiB"
+      bootable: true
+      type: *bios_boot_partition_guid
+    - size: "501 MiB"
+      type: *efi_system_partition_guid
+      payload_type: "filesystem"
+      payload:
+        type: vfat
+        mountpoint: "/boot/efi"
+        label: "EFI-SYSTEM"
+        fstab_options: "umask=0077,shortname=winnt"
+        fstab_freq: 0
+        fstab_passno: 2
+    - size: "4 GiB"
+      type: *filesystem_data_guid
+      payload_type: "filesystem"
+      payload:
+        type: xfs
+        label: "root"
+        mountpoint: "/"
+        fstab_options: "ro"
+DISKEOF
+' | save Dockerfile
+    podman build -t localhost/bootc-bib-test .
+
+    # Create output directory for bib
+    mkdir output
+
+    # Run bootc-image-builder to create a qcow2
+    # We use --local to pull from local containers-storage
+    # The embedded disk.yaml will be used for partitioning
+    print "=== Running bootc-image-builder ==="
+    let bib_image = $BIB_IMAGE
+    # Note: we disable SELinux labeling since we're running in a test VM
+    # and use unconfined_t to avoid permission issues
+    podman run --rm --privileged -v /var/lib/containers/storage:/var/lib/containers/storage --security-opt label=type:unconfined_t -v ./output:/output $bib_image --type qcow2 --local localhost/bootc-bib-test
+
+    # Verify output was created
+    print "=== Verifying output ==="
+    let disk_path = "output/qcow2/disk.qcow2"
+    assert ($disk_path | path exists) $"Expected disk image at ($disk_path)"
+
+    # Check the disk has reasonable virtual size (at least 4GB as per disk.yaml)
+    # Note: qcow2 files are sparse, so file size != virtual size
+    # We use qemu-img to get the actual virtual disk size
+    let info = qemu-img info --output=json $disk_path | from json
+    let virtual_size = $info | get virtual-size
+    print $"Disk image virtual size: ($virtual_size | into filesize)"
+    # The disk.yaml specifies ~4.5 GiB total, so virtual size should be at least 4 GiB
+    assert ($virtual_size > 4000000000) "Disk image virtual size seems too small"
+
+    # Also print file size for reference (qcow2 is sparse/compressed)
+    let file_size = ls $disk_path | get size | first
+    print $"Disk image file size: ($file_size)"
+
+    print "=== Success: bootc-image-builder created disk image ==="
+    tap ok
+}

tmt/tests/tests.fmf

@@ -89,3 +89,10 @@
   - dosfstools
   - e2fsprogs
   test: bash booted/test-install-to-filesystem-var-mount.sh
+
+/test-33-bib-build:
+  summary: Test building a qcow2 disk image with bootc-image-builder
+  duration: 45m
+  require:
+  - qemu-img
+  test: nu booted/test-bib-build.nu