Add end-to-end test for disjoint_tree_overlay

... and verify that
- spurious conflicts do not cause failure but instead are handled
  correctly, and
- real conflicts are detected and reported properly.

2 files changed, 90 insertions, 0 deletions

diff --git a/test/end-to-end/actions/TARGETS b/test/end-to-end/actions/TARGETS
index 23b1be4f..5258dc0c 100644
--- a/test/end-to-end/actions/TARGETS
+++ b/test/end-to-end/actions/TARGETS
@@ -97,6 +97,13 @@
   , "deps": [["", "tool-under-test"]]
   , "keep": ["out/graph.json", "out/artifacts.json"]
   }
+, "tree-conflicts":
+  { "type": ["@", "rules", "shell/test", "script"]
+  , "name": ["tree-conflcits"]
+  , "test": ["tree-conflicts.sh"]
+  , "deps": [["", "tool-under-test"]]
+  , "keep": ["out/graph.json", "out/artifacts.json", "out/log"]
+  }
 , "TESTS":
   { "type": ["@", "rules", "test", "suite"]
   , "arguments_config": ["DROP_IO_HEAVY_TESTS"]
@@ -109,6 +116,7 @@
         , "equality-properties"
         , "trees"
         , "tree-ops"
+        , "tree-conflicts"
         , "conflicts"
         , "incomplete-retry"
         , "error-reporting"
diff --git a/test/end-to-end/actions/tree-conflicts.sh b/test/end-to-end/actions/tree-conflicts.sh
new file mode 100644
index 00000000..87b1f489
--- /dev/null
+++ b/test/end-to-end/actions/tree-conflicts.sh
@@ -0,0 +1,82 @@
+#!/bin/sh
+# Copyright 2025 Huawei Cloud Computing Technology Co., Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -e
+
+readonly ROOT="$(pwd)"
+readonly LBR="${TMPDIR}/local-build-root"
+readonly OUT="${ROOT}/out"
+mkdir -p "${OUT}"
+readonly JUST="${ROOT}/bin/tool-under-test"
+
+mkdir work
+cd work
+touch ROOT
+
+cat > TARGETS <<'EOF'
+{ "foo":
+  { "type": "generic"
+  , "out_dirs": ["out"]
+  , "cmds": ["mkdir -p out", "echo FOO > out/foo", "echo FOOBAR > out/foobar"]
+  }
+, "good bar":
+  { "type": "generic"
+  , "out_dirs": ["out"]
+  , "cmds": ["mkdir -p out", "echo BAR > out/bar", "echo FOOBAR > out/foobar"]
+  }
+, "bad bar":
+  { "type": "generic"
+  , "out_dirs": ["out"]
+  , "cmds": ["mkdir -p out", "echo BAR > out/bar", "echo foobar > out/foobar"]
+  }
+, "spurious conflict":
+  { "type": "disjoint_tree_overlay"
+  , "name": "merge"
+  , "deps": ["foo", "good bar"]
+  }
+, "real conflict":
+  { "type": "disjoint_tree_overlay"
+  , "name": "merge"
+  , "deps": ["foo", "bad bar"]
+  }
+}
+EOF
+
+# In case of a spourious conflict, things should just build
+"${JUST}" install --local-build-root "${LBR}" -o "${OUT}/spurious" \
+          -L '["env", "PATH='"${PATH}"'"]' 'spurious conflict' 2>&1
+grep FOO "${OUT}/spurious/merge/out/foo"
+grep BAR "${OUT}/spurious/merge/out/bar"
+grep FOOBAR "${OUT}/spurious/merge/out/foobar"
+
+# In case of a real conflict, analysis should still work
+"${JUST}" analyse --local-build-root "${LBR}" \
+          --dump-graph "${OUT}/graph.json" \
+          --dump-artifacts-to-build "${OUT}/artifacts.json" \
+          'real conflict' 2>&1
+echo
+[ "$(jq -r '.merge.type' "${OUT}/artifacts.json")" = TREE_OVERLAY ]
+OVERLAY_ID=$(jq -r '.merge.data.id' "${OUT}/artifacts.json")
+[ "$(jq '."tree_overlays"."'"${OVERLAY_ID}"'".trees | length' "${OUT}/graph.json")" -eq 2 ]
+
+# Building should fail, however
+"${JUST}" build --local-build-root "${LBR}" \
+          -f "${OUT}/log" \
+          -L '["env", "PATH='"${PATH}"'"]' 'real conflict' 2>&1 && exit 1 || :
+echo
+grep 'foobar' "${OUT}/log" # The location of the conflict should be mentioned
+
+echo
+echo OK