add test

Author: SteveL-MSFT

dsc/tests/dsc_tracing.tests.ps1

@@ -85,4 +85,16 @@ Describe 'tracing tests' {
         $out = (dsc -l $level config get -d $configYaml 2> $null) | ConvertFrom-Json
         $out.results[0].result.actualState.level | Should -BeExactly $level
     }
+
+    It 'Pass-through tracing should only emit JSON for child processes' {
+        $logPath = "$TestDrive/dsc_trace.log"
+        $out = dsc -l info -f pass-through  config get -p ../examples/groups.dsc.yaml 2> $logPath
+        foreach ($line in (Get-Content $logPath)) {
+            $line | Should -Not -BeNullOrEmpty
+            $json = $line | ConvertFrom-Json
+            $json.timestamp | Should -Not -BeNullOrEmpty
+            $json.level | Should -BeIn 'ERROR', 'WARN', 'INFO', 'DEBUG', 'TRACE'
+        }
+        $out | Should -BeNullOrEmpty
+    }
 }