Add some basic CI for FindBotan.cmake.

Squashed commits:
[85b3a83] chore: gha move FindBotan job inside matrix

Author: ni4

.github/workflows/centos8.yml

@@ -27,8 +27,10 @@ jobs:
             ci: findossl
           - name: PandocMan.cmake
             ci: pandocman
+          - name: FindBotan.cmake
+            ci: findbotan
       fail-fast: false
-    name: CMake modules check
+    name: Check CMake module
     steps:
       - run: |
           dnf -y install git
@@ -80,3 +82,19 @@ jobs:
           man ./testpandoc.1
           man testpandoc
           popd
+      - name: Check FindBotan.cmake
+        if: matrix.module.name == 'FindBotan.cmake'
+        run: |
+          set -eux
+          sudo dnf -y -q install python3-devel
+          git clone --depth 1 --branch 2.19.3 https://github.com/randombit/botan.git
+          pushd botan
+          python3 configure.py && make -j2 && make -j2 install
+          popd
+          mkdir "${GITHUB_WORKSPACE}/build"
+          pushd "${GITHUB_WORKSPACE}/build"
+          cmake "${GITHUB_WORKSPACE}/ci/findbotan" "-DCMAKE_MODULE_PATH=${GITHUB_WORKSPACE}"
+          grep -q "/usr/local/lib/libbotan-2.so" "${GITHUB_WORKSPACE}/ci/findbotan/findbotan.txt"
+          grep -q "/usr/local/include/botan-2" "${GITHUB_WORKSPACE}/ci/findbotan/findbotan.txt"
+          popd
+

ci/findbotan/CMakeLists.txt

@@ -0,0 +1,19 @@
+cmake_minimum_required(VERSION 3.14)
+
+project(test-findbotan
+  LANGUAGES C
+)
+
+include(FindBotan)
+find_package(Botan 2.0 REQUIRED)
+
+file(WRITE findbotan.txt "BOTAN_LIBRARY: ${BOTAN_LIBRARY}\n")
+file(APPEND findbotan.txt "BOTAN_INCLUDE_DIR: ${BOTAN_INCLUDE_DIR}\n")
+
+if(NOT DEFINED BOTAN_LIBRARY OR "${BOTAN_LIBRARY}" STREQUAL "")
+  message(FATAL_ERROR "BOTAN_LIBRARY is not set.")
+endif()
+
+if(NOT DEFINED BOTAN_INCLUDE_DIR OR "${BOTAN_INCLUDE_DIR}" STREQUAL "")
+  message(FATAL_ERROR "BOTAN_INCLUDE_DIR is not set.")
+endif()