initial commit: docker test-build toolchain

Extracted from the .extras/ dir of the sbo-slackbuilds package repo, where it
grew from a throwaway helper into a standalone tool. Git history starts fresh;
the original 41-commit development log is preserved in HISTORY.md.

Contents: the test-build CLI (resolves a local SlackBuild's deps from a
configured SBo tree and builds it in a throwaway container, lints, caches deps),
the image-builder chain that produces the images it consumes, their pure-logic
self-checks, design specs/plans, an install.sh for ~/bin, and docs.

Licensed GPLv2-only.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

1 files changed, 80 insertions, 0 deletions

diff --git a/image-builder/test-image-builder.sh b/image-builder/test-image-builder.sh
new file mode 100755
index 0000000..525ea8f
--- /dev/null
+++ b/image-builder/test-image-builder.sh
@@ -0,0 +1,80 @@
+#!/bin/bash
+#
+# Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# Assert-based self-check for lib.sh pure logic. No docker, no network.
+# Run: bash test-image-builder.sh
+set -u
+cd "$(dirname "$0")"
+source ./lib.sh
+
+pass=0 fail=0
+check() { # DESC EXPECTED ACTUAL
+    if [[ "$2" == "$3" ]]; then pass=$((pass+1));
+    else fail=$((fail+1)); echo "FAIL: $1"; echo "  expected: [$2]"; echo "  actual:   [$3]"; fi
+}
+check_rc() { # DESC EXPECTED_RC ACTUAL_RC
+    if [[ "$2" == "$3" ]]; then pass=$((pass+1));
+    else fail=$((fail+1)); echo "FAIL: $1 (rc expected $2 got $3)"; fi
+}
+
+tmp="$(mktemp -d)"
+trap 'rm -rf "$tmp"' EXIT
+
+# --- mirror_path ---
+check "mirror_path trailing slash" \
+    "file:///mnt/nas/slackware64-current/PACKAGES.TXT" \
+    "$(mirror_path 'file:///mnt/nas/' 'slackware64-current/PACKAGES.TXT')"
+check "mirror_path no trailing slash" \
+    "file:///mnt/nas/x/y" "$(mirror_path 'file:///mnt/nas' '/x/y')"
+
+# --- is_local_mirror ---
+is_local_mirror "file:///mnt/nas"; check_rc "is_local file://" 0 $?
+is_local_mirror "/mnt/nas";        check_rc "is_local bare abs" 0 $?
+is_local_mirror "https://x/y";     check_rc "is_local https" 1 $?
+
+# --- strip_scheme ---
+check "strip_scheme file://" "/mnt/nas" "$(strip_scheme 'file:///mnt/nas')"
+check "strip_scheme bare" "/mnt/nas" "$(strip_scheme '/mnt/nas')"
+
+# --- fetch: local file resolves ---
+echo hello > "$tmp/src.txt"
+fetch "file://$tmp/src.txt" "$tmp/dst.txt"; check_rc "fetch local ok" 0 $?
+check "fetch local content" "hello" "$(cat "$tmp/dst.txt" 2>/dev/null)"
+
+# --- fetch: missing local file errors ---
+fetch "file://$tmp/nope.txt" "$tmp/x.txt"; check_rc "fetch local missing" 1 $?
+
+# --- txz_hash: stable + content-sensitive ---
+mkdir -p "$tmp/pkgs"
+printf a > "$tmp/pkgs/sbopkg-1.txz"
+printf b > "$tmp/pkgs/tools-1.txz"
+h1="$(txz_hash "$tmp/pkgs")"
+h2="$(txz_hash "$tmp/pkgs")"
+check "txz_hash stable" "$h1" "$h2"
+printf c > "$tmp/pkgs/tools-1.txz"   # change content
+h3="$(txz_hash "$tmp/pkgs")"
+check_rc "txz_hash changes on content" 0 "$([[ "$h1" != "$h3" ]] && echo 0 || echo 1)"
+check "txz_hash empty dir" "" "$(txz_hash "$tmp/empty-nope")"
+
+# --- require_mount: missing mount errors (subshell to catch _err exit) ---
+MIRROR="file://$tmp/no-such-root"
+( require_mount current ) 2>/dev/null; check_rc "require_mount missing" 1 $?
+mkdir -p "$tmp/mnt/slackware64-current"
+MIRROR="file://$tmp/mnt"
+( require_mount current ) 2>/dev/null; check_rc "require_mount present" 0 $?
+MIRROR="https://example/x"
+( require_mount current ) 2>/dev/null; check_rc "require_mount http skips" 0 $?
+
+echo "----"
+echo "PASS: $pass  FAIL: $fail"
+[[ "$fail" -eq 0 ]]