test: improve code coverage of diagnostics_channel

test/parallel/test-diagnostics-channel-tracing-channel-args-types.js

@@ -0,0 +1,39 @@
+'use strict';
+
+require('../common');
+const dc = require('diagnostics_channel');
+const assert = require('assert');
+
+let channel;
+
+// tracingChannel creating with name
+channel = dc.tracingChannel('test');
+assert.strictEqual(channel.start.name, 'tracing:test:start');
+
+// tracingChannel creating with channels
+channel = dc.tracingChannel({
+  start: dc.channel('tracing:test:start'),
+  end: dc.channel('tracing:test:end'),
+  asyncStart: dc.channel('tracing:test:asyncStart'),
+  asyncEnd: dc.channel('tracing:test:asyncEnd'),
+  error: dc.channel('tracing:test:error'),
+});
+
+// tracingChannel creating without nameOrChannels must throw TypeError
+assert.throws(() => (channel = dc.tracingChannel(0)), {
+  code: 'ERR_INVALID_ARG_TYPE',
+  name: 'TypeError',
+  message:
+    /The "nameOrChannels" argument must be of type string or an instance of Channel or Object/,
+});
+
+// tracingChannel creating without instance of Channel must throw error
+assert.throws(() => (channel = dc.tracingChannel({ start: '' })), {
+  code: 'ERR_INVALID_ARG_TYPE',
+  message: /The "nameOrChannels\.start" property must be an instance of Channel/,
+});
+
+// tracingChannel creating with empty nameOrChannels must throw error
+assert.throws(() => (channel = dc.tracingChannel({})), {
+  message: /Cannot convert undefined or null to object/,
+});