Improve error messages on reading invalid target files

... by including the details of the parse error.

2 files changed, 53 insertions, 1 deletions

diff --git a/test/end-to-end/user-errors/TARGETS b/test/end-to-end/user-errors/TARGETS
index cb1b881e..f12f6151 100644
--- a/test/end-to-end/user-errors/TARGETS
+++ b/test/end-to-end/user-errors/TARGETS
@@ -4,5 +4,15 @@
   , "test": ["flat-stage.sh"]
   , "deps": [["test/end-to-end", "tool-under-test"]]
   }
-, "TESTS": {"type": "install", "tainted": ["test"], "deps": ["flat-stage"]}
+, "json-errors":
+  { "type": ["@", "rules", "shell/test", "script"]
+  , "name": ["json-errors"]
+  , "test": ["json-errors.sh"]
+  , "deps": [["test/end-to-end", "tool-under-test"]]
+  }
+, "TESTS":
+  { "type": "install"
+  , "tainted": ["test"]
+  , "deps": ["flat-stage", "json-errors"]
+  }
 }
diff --git a/test/end-to-end/user-errors/json-errors.sh b/test/end-to-end/user-errors/json-errors.sh
new file mode 100755
index 00000000..ec57c962
--- /dev/null
+++ b/test/end-to-end/user-errors/json-errors.sh
@@ -0,0 +1,42 @@
+#!/bin/sh
+# Copyright 2023 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="${PWD}"
+readonly JUST="${ROOT}/bin/tool-under-test"
+readonly LBR="${TEST_TMPDIR}/local-build-root"
+
+touch ROOT
+cat > TARGETS <<'EOF'
+{ "THIS": would be the default target if it where syntactically correct ...
+EOF
+
+"${JUST}" build --local-build-root "${LBR}" 2>msg && exit 1 || :
+cat msg
+grep -q 'default target' msg
+grep -q 'TARGETS' msg
+grep -q 'line' msg # expect  to see a position of the parsing error
+grep -q '"THIS"' msg # expect to see the last valid token
+
+
+"${JUST}" build --local-build-root "${LBR}" some-target 2>msg && exit 1 || :
+cat msg
+# expect the error to happen while trying to analyse the default target
+grep -q '["@","","","some-target"]' msg
+grep -q 'line' msg # expect  to see a position of the parsing error
+grep -q '"THIS"' msg # expect to see the last valid token
+
+echo OK