Added new testing framework for linting tests

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Ole Herman Schumacher Elgesem <ole.elgesem@northern.tech>

Author: olehermanse

tests/lint/001_hello_world.cf

@@ -0,0 +1,5 @@
+bundle agent main
+{
+  reports:
+    "Hello, world!";
+}

tests/lint/002_ifvarclass.output.txt

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+
+    "Hello, CFEngine"
+      ifvarclass => "cfengine";
+      ^--------^
+Deprecation: Use 'if' instead of 'ifvarclass' at tests/lint/002_ifvarclass.x.cf:5:7
+FAIL: tests/lint/002_ifvarclass.x.cf (1 errors)
+Failure, 1 errors in total.

tests/lint/002_ifvarclass.x.cf

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+bundle agent main
+{
+  reports:
+    "Hello, CFEngine"
+      ifvarclass => "cfengine";
+}

tests/run-lint-tests.sh

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+#/usr/bin/env bash
+
+set -e
+# set -x
+
+echo "These tests expect cfengine CLI to be installed globally or in venv"
+
+echo "Looking for CFEngine CLI:"
+which cfengine
+
+echo "Check that test files are in expected location:"
+ls -al tests/lint/*.cf
+
+mkdir -p tmp
+
+echo "Run lint tests:"
+for file in tests/lint/*.cf; do
+  if echo "$file" | grep -q '\.x\.cf$'; then
+    # File ends with .x.cf, we expect it to:
+    #  - Fail (non-zero exit code)
+    #  - Output the correct error message
+
+    expected="$(echo $file | sed 's/\.x\.cf$/.output.txt/')"
+    if [ ! -f "$expected" ]; then
+      echo "FAIL: Missing expected output file: $expected"
+      exit 1
+    fi
+    output="tmp/$(basename $file .x.cf).lint-output.txt"
+    if cfengine lint "$file" > "$output" 2>&1; then
+      echo "FAIL: $file - expected lint failure but got success"
+      exit 1
+    fi
+    diff -u "$expected" "$output"
+    echo "OK (expected failure): $file"
+  else
+    # Expect success
+    if ! cfengine lint "$file"; then
+      echo "FAIL: $file - expected lint success but got failure"
+      exit 1
+    fi
+    echo "OK: $file"
+  fi
+done
+
+echo "All lint tests successful!"