Introduce plausibility check for outbound licenes

When creating a library or executable, several source files are combined
into a binary artifact that has an outbound license of its own. This test
generator allows to check if the combined source files are compatible
with the desired outbound license.

Requirements for using these tests:
- input source files must contain the SPDX-License-Information tag
- python3 must be available
- the "reuse spdx" tool must be available

1 files changed, 23 insertions, 0 deletions

diff --git a/find-modules/FindReuseTool.cmake b/find-modules/FindReuseTool.cmake
new file mode 100644
index 00000000..9377f49e
--- /dev/null
+++ b/find-modules/FindReuseTool.cmake
@@ -0,0 +1,23 @@
+# WARNING: FOR ECM-INTERNAL USE ONLY, DO NOT USE IN OWN PROJECTS
+# THIS FILE MIGHT DISAPPEAR IN FUTURE VERSIONS OF ECM.
+
+# Finds the REUSE Tool by FSFE: https://github.com/fsfe/reuse-tool
+#
+#  REUSE_TOOL_FOUND      - True if REUSE tool is found.
+#  REUSE_TOOL_EXECUTABLE - Path to executable
+
+#=============================================================================
+# SPDX-FileCopyrightText: 2020 Andreas Cord-Landwehr <cordlandwehr@kde.org>
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#=============================================================================
+
+find_program(REUSETOOL_EXECUTABLE NAMES reuse)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(ReuseTool
+    FOUND_VAR
+        REUSETOOL_FOUND
+    REQUIRED_VARS
+        REUSE_TOOL_EXECUTABLE
+)