[minor] Adding minimal test case

test.js

@@ -0,0 +1,80 @@
+describe('diagnostics', function () {
+  'use strict';
+
+  var assume = require('assume')
+    , debug = require('./');
+
+  beforeEach(function () {
+    process.env.DEBUG = '';
+  });
+
+  it('is exposed as function', function () {
+    assume(debug).to.be.a('function');
+  });
+
+  describe('.enabled', function () {
+    it('uses the `debug` env', function () {
+      process.env.DEBUG = 'bigpipe';
+
+      assume(debug.enabled('bigpipe')).to.be.true();
+      assume(debug.enabled('false')).to.be.false();
+    });
+
+    it('uses the `diagnostics` env', function () {
+      process.env.DIAGNOSTICS = 'bigpipe';
+
+      assume(debug.enabled('bigpipe')).to.be.true();
+      assume(debug.enabled('false')).to.be.false();
+    });
+
+    it('supports wildcards', function () {
+      process.env.DEBUG = 'b*';
+
+      assume(debug.enabled('bigpipe')).to.be.true();
+      assume(debug.enabled('bro-fist')).to.be.true();
+      assume(debug.enabled('ro-fist')).to.be.false();
+    });
+
+    it('is disabled by default', function () {
+      process.env.DEBUG = '';
+
+      assume(debug.enabled('bigpipe')).to.be.false();
+
+      process.env.DEBUG = 'bigpipe';
+
+      assume(debug.enabled('bigpipe')).to.be.true();
+    });
+
+    it('can ignore loggers using a -', function () {
+      process.env.DEBUG = 'bigpipe,-primus,sack';
+
+      assume(debug.enabled('bigpipe')).to.be.true();
+      assume(debug.enabled('sack')).to.be.true();
+      assume(debug.enabled('primus')).to.be.false();
+      assume(debug.enabled('unknown')).to.be.false();
+    });
+  });
+
+  describe('.resolve', function () {
+    it('automatically finds a suitable name', function () {
+      assume(debug.resolve(module)).to.not.equal('');
+    });
+  });
+
+  describe('.to', function (next) {
+    it('globally overrides the stream', function () {
+      debug.to({
+        write: function write(line) {
+          assume(line).to.contain('foo');
+          assume(line).to.contain('bar');
+
+          debug.to(process.stdout);
+          next();
+        }
+      });
+
+      var log = debug('foo');
+      log('bar');
+    });
+  });
+});