Ensure process object exists for deprecation warn

Fix: #206
PR-URL: #207
Credit: @tavogel
Close: #207
Reviewed-by: @isaacs

Author: tavogel

Diff for: index.js

@@ -24,7 +24,9 @@ const deprecatedProperty = (field, instead) => {
     warn(code, `${field} property`, `cache.${instead}`, get)
   }
 }
-const shouldWarn = (code) => !(process.noDeprecation || warned.has(code))
+const shouldWarn = (code) => typeof process === 'object' &&
+  process &&
+  !(process.noDeprecation || warned.has(code))
 const warn = (code, what, instead, fn) => {
   warned.add(code)
   process.emitWarning(`The ${what} is deprecated. Please use ${instead} instead.`, 'DeprecationWarning', code, fn)

Diff for: tap-snapshots/test/deprecations.js.test.cjs

@@ -5,7 +5,7 @@
  * Make sure to inspect the output below.  Do not ignore changes!
  */
 'use strict'
-exports[`test/deprecations.js TAP > must match snapshot 1`] = `
+exports[`test/deprecations.js TAP warns exactly once for a given deprecation > must match snapshot 1`] = `
 Array [
   Array [
     "The stale option is deprecated. Please use options.allowStale instead.",

Diff for: test/deprecations.js

@@ -5,32 +5,61 @@ process.noDeprecation = false
 const warnings = []
 process.emitWarning = (...w) => warnings.push(w)
 
-const c = new LRU({
-  max: 100,
-  maxSize: 100,
-  maxAge: 1000,
-  stale: true,
-  length: n => 1,
-})
-c.reset()
-t.equal(c.length, 0)
-t.equal(c.prune, c.purgeStale)
-t.equal(c.reset, c.clear)
-t.equal(c.del, c.delete)
-
-t.matchSnapshot(warnings)
-
-warnings.length = 0
-const d = new LRU({
-  max: 100,
-  maxSize: 100,
-  maxAge: 1000,
-  stale: true,
-  length: n => 1,
+t.test('warns exactly once for a given deprecation', t => {
+  const c = new LRU({
+    max: 100,
+    maxSize: 100,
+    maxAge: 1000,
+    stale: true,
+    length: n => 1,
+  })
+  c.reset()
+  t.equal(c.length, 0)
+  t.equal(c.prune, c.purgeStale)
+  t.equal(c.reset, c.clear)
+  t.equal(c.del, c.delete)
+
+  t.matchSnapshot(warnings)
+
+  warnings.length = 0
+  const d = new LRU({
+    max: 100,
+    maxSize: 100,
+    maxAge: 1000,
+    stale: true,
+    length: n => 1,
+  })
+  d.reset()
+
+  t.equal(d.length, 0)
+  t.equal(d.prune, d.purgeStale)
+  t.equal(d.reset, d.clear)
+  t.strictSame(warnings, [], 'only warn once')
+
+  warnings.length = 0
+  t.end()
 })
-d.reset()
 
-t.equal(d.length, 0)
-t.equal(d.prune, d.purgeStale)
-t.equal(d.reset, d.clear)
-t.strictSame(warnings, [], 'only warn once')
+t.test('does not do deprecation warning without process object', t => {
+  // set process to null (emulate a browser)
+  const proc = process
+  t.teardown(() => global.process = proc)
+  global.process = null
+
+  const c = new LRU({
+    max: 100,
+    maxSize: 100,
+    maxAge: 1000,
+    stale: true,
+    length: n => 1,
+  })
+  c.reset()
+  t.equal(c.length, 0)
+  t.equal(c.prune, c.purgeStale)
+  t.equal(c.reset, c.clear)
+  t.equal(c.del, c.delete)
+
+  t.strictSame(warnings, [], 'no process exists')
+
+  t.end()
+})