diff --git a/benchmark/assert/deepequal-buffer.js b/benchmark/assert/deepequal-buffer.js
index 6d9162f15173f9..69cca91cc6d752 100644
--- a/benchmark/assert/deepequal-buffer.js
+++ b/benchmark/assert/deepequal-buffer.js
@@ -6,12 +6,10 @@ const bench = common.createBenchmark(main, {
   n: [2e4],
   len: [1e2, 1e3],
   strict: [0, 1],
-  method: [ 'deepEqual', 'notDeepEqual' ],
+  method: ['deepEqual', 'notDeepEqual'],
 });
 
 function main({ len, n, method, strict }) {
-  if (!method)
-    method = 'deepEqual';
   const data = Buffer.allocUnsafe(len + 1);
   const actual = Buffer.alloc(len);
   const expected = Buffer.alloc(len);
diff --git a/benchmark/assert/deepequal-map.js b/benchmark/assert/deepequal-map.js
index b88ecf7ce127f9..77408e3d103475 100644
--- a/benchmark/assert/deepequal-map.js
+++ b/benchmark/assert/deepequal-map.js
@@ -34,8 +34,6 @@ function main({ n, len, method, strict }) {
   const array = Array(len).fill(1);
 
   switch (method) {
-    case '':
-      // Empty string falls through to next line as default, mostly for tests.
     case 'deepEqual_primitiveOnly': {
       const values = array.map((_, i) => [`str_${i}`, 123]);
       benchmark(strict ? deepStrictEqual : deepEqual, n, values);
diff --git a/benchmark/assert/deepequal-object.js b/benchmark/assert/deepequal-object.js
index e23f6692b3decd..a8c539426a8156 100644
--- a/benchmark/assert/deepequal-object.js
+++ b/benchmark/assert/deepequal-object.js
@@ -7,7 +7,7 @@ const bench = common.createBenchmark(main, {
   n: [5e3],
   size: [1e2, 1e3, 5e4],
   strict: [0, 1],
-  method: [ 'deepEqual', 'notDeepEqual' ],
+  method: ['deepEqual', 'notDeepEqual'],
 });
 
 function createObj(source, add = '') {
@@ -27,9 +27,6 @@ function main({ size, n, method, strict }) {
   // TODO: Fix this "hack". `n` should not be manipulated.
   n = Math.min(Math.ceil(n / size), 20);
 
-  if (!method)
-    method = 'deepEqual';
-
   const source = Array.apply(null, Array(size));
   const actual = createObj(source);
   const expected = createObj(source);
diff --git a/benchmark/assert/deepequal-prims-and-objs-big-array-set.js b/benchmark/assert/deepequal-prims-and-objs-big-array-set.js
index 0e0ce450bb1a98..ad049ded02ce9d 100644
--- a/benchmark/assert/deepequal-prims-and-objs-big-array-set.js
+++ b/benchmark/assert/deepequal-prims-and-objs-big-array-set.js
@@ -52,8 +52,6 @@ function main({ n, len, primitive, method, strict }) {
   const expectedWrongSet = new Set(expectedWrong);
 
   switch (method) {
-    // Empty string falls through to next line as default, mostly for tests.
-    case '':
     case 'deepEqual_Array':
       run(strict ? deepStrictEqual : deepEqual, n, actual, expected);
       break;
diff --git a/benchmark/assert/deepequal-prims-and-objs-big-loop.js b/benchmark/assert/deepequal-prims-and-objs-big-loop.js
index 32140f08ded6fb..2d01431b1fc563 100644
--- a/benchmark/assert/deepequal-prims-and-objs-big-loop.js
+++ b/benchmark/assert/deepequal-prims-and-objs-big-loop.js
@@ -13,12 +13,10 @@ const bench = common.createBenchmark(main, {
   primitive: Object.keys(primValues),
   n: [2e4],
   strict: [0, 1],
-  method: [ 'deepEqual', 'notDeepEqual' ],
+  method: ['deepEqual', 'notDeepEqual'],
 });
 
 function main({ n, primitive, method, strict }) {
-  if (!method)
-    method = 'deepEqual';
   const prim = primValues[primitive];
   const actual = prim;
   const expected = prim;
diff --git a/benchmark/assert/deepequal-set.js b/benchmark/assert/deepequal-set.js
index 561a951e6834cc..27ca7c92bce1b0 100644
--- a/benchmark/assert/deepequal-set.js
+++ b/benchmark/assert/deepequal-set.js
@@ -34,8 +34,6 @@ function main({ n, len, method, strict }) {
   const array = Array(len).fill(1);
 
   switch (method) {
-    case '':
-      // Empty string falls through to next line as default, mostly for tests.
     case 'deepEqual_primitiveOnly': {
       const values = array.map((_, i) => `str_${i}`);
       benchmark(strict ? deepStrictEqual : deepEqual, n, values);
diff --git a/benchmark/assert/deepequal-typedarrays.js b/benchmark/assert/deepequal-typedarrays.js
index 10ba21a25759e2..188cfce695ed61 100644
--- a/benchmark/assert/deepequal-typedarrays.js
+++ b/benchmark/assert/deepequal-typedarrays.js
@@ -20,8 +20,6 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ type, n, len, method, strict }) {
-  if (!method)
-    method = 'deepEqual';
   const clazz = global[type];
   const actual = new clazz(len);
   const expected = new clazz(len);
diff --git a/benchmark/assert/throws.js b/benchmark/assert/throws.js
index c80518377a8742..978ad2f1b8bef0 100644
--- a/benchmark/assert/throws.js
+++ b/benchmark/assert/throws.js
@@ -15,8 +15,6 @@ function main({ n, method }) {
   const message = 'failure';
 
   switch (method) {
-    case '':
-      // Empty string falls through to next line as default, mostly for tests.
     case 'doesNotThrow':
       bench.start();
       for (let i = 0; i < n; ++i) {
diff --git a/benchmark/buffers/buffer-bytelength.js b/benchmark/buffers/buffer-bytelength.js
index 1b324a49f89de8..fbbe0f040da56a 100644
--- a/benchmark/buffers/buffer-bytelength.js
+++ b/benchmark/buffers/buffer-bytelength.js
@@ -17,9 +17,9 @@ const chars = [
 
 function main({ n, len, encoding }) {
   let strings = [];
-  let results = [ len * 16 ];
+  let results = [len * 16];
   if (encoding === 'buffer') {
-    strings = [ Buffer.alloc(len * 16, 'a') ];
+    strings = [Buffer.alloc(len * 16, 'a')];
   } else {
     for (const string of chars) {
       // Strings must be built differently, depending on encoding
diff --git a/benchmark/buffers/buffer-creation.js b/benchmark/buffers/buffer-creation.js
index 38d80da915c070..862bff4fbabe58 100644
--- a/benchmark/buffers/buffer-creation.js
+++ b/benchmark/buffers/buffer-creation.js
@@ -16,7 +16,6 @@ const bench = common.createBenchmark(main, {
 function main({ len, n, type }) {
   let fn, i;
   switch (type) {
-    case '':
     case 'fast-alloc':
       fn = Buffer.alloc;
       break;
diff --git a/benchmark/buffers/buffer-fill.js b/benchmark/buffers/buffer-fill.js
index 02bc2a206c6fe3..8d4d4996068224 100644
--- a/benchmark/buffers/buffer-fill.js
+++ b/benchmark/buffers/buffer-fill.js
@@ -22,7 +22,7 @@ function main({ n, type, size }) {
   const buffer = Buffer.allocUnsafe(size);
   const testFunction = new Function('b', `
     for (var i = 0; i < ${n}; i++) {
-      b.${type || 'fill(0)'};
+      b.${type};
     }
   `);
   bench.start();
diff --git a/benchmark/buffers/buffer-iterate.js b/benchmark/buffers/buffer-iterate.js
index de002108a95d65..3e2a897903d435 100644
--- a/benchmark/buffers/buffer-iterate.js
+++ b/benchmark/buffers/buffer-iterate.js
@@ -21,7 +21,7 @@ function main({ size, type, method, n }) {
     Buffer.alloc(size) :
     SlowBuffer(size).fill(0);
 
-  const fn = methods[method || 'for'];
+  const fn = methods[method];
 
   bench.start();
   fn(buffer, n);
diff --git a/benchmark/buffers/buffer-read-float.js b/benchmark/buffers/buffer-read-float.js
index e8c4f8bf549628..656762d1d4f1d0 100644
--- a/benchmark/buffers/buffer-read-float.js
+++ b/benchmark/buffers/buffer-read-float.js
@@ -9,7 +9,6 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ n, type, endian, value }) {
-  type = type || 'Double';
   const buff = Buffer.alloc(8);
   const fn = `read${type}${endian}`;
   const values = {
diff --git a/benchmark/buffers/buffer-read-with-byteLength.js b/benchmark/buffers/buffer-read-with-byteLength.js
index 6ba1594b8ac6eb..c51ab11ae986d7 100644
--- a/benchmark/buffers/buffer-read-with-byteLength.js
+++ b/benchmark/buffers/buffer-read-with-byteLength.js
@@ -19,7 +19,7 @@ function main({ n, buf, type, byteLength }) {
   const buff = buf === 'fast' ?
     Buffer.alloc(8) :
     require('buffer').SlowBuffer(8);
-  const fn = `read${type || 'IntBE'}`;
+  const fn = `read${type}`;
 
   buff.writeDoubleLE(0, 0);
   bench.start();
diff --git a/benchmark/buffers/buffer-read.js b/benchmark/buffers/buffer-read.js
index 2ddca60df44c29..e0ec13992c2fae 100644
--- a/benchmark/buffers/buffer-read.js
+++ b/benchmark/buffers/buffer-read.js
@@ -28,7 +28,7 @@ function main({ n, buf, type }) {
   const buff = buf === 'fast' ?
     Buffer.alloc(8) :
     require('buffer').SlowBuffer(8);
-  const fn = `read${type || 'UInt8'}`;
+  const fn = `read${type}`;
 
   buff.writeDoubleLE(0, 0);
   bench.start();
diff --git a/benchmark/buffers/buffer-swap.js b/benchmark/buffers/buffer-swap.js
index 5c31d86f7e2ab4..e43957efbdb095 100644
--- a/benchmark/buffers/buffer-swap.js
+++ b/benchmark/buffers/buffer-swap.js
@@ -76,7 +76,7 @@ function genMethod(method) {
 
 function main({ method, len, n, aligned = 'true' }) {
   const buf = createBuffer(len, aligned === 'true');
-  const bufferSwap = genMethod(method || 'swap16');
+  const bufferSwap = genMethod(method);
 
   bufferSwap(n, buf);
   bench.start();
diff --git a/benchmark/buffers/buffer-write.js b/benchmark/buffers/buffer-write.js
index db5a57d0023e72..5025dd2bca0407 100644
--- a/benchmark/buffers/buffer-write.js
+++ b/benchmark/buffers/buffer-write.js
@@ -74,7 +74,7 @@ function main({ n, buf, type }) {
   const buff = buf === 'fast' ?
     Buffer.alloc(8) :
     require('buffer').SlowBuffer(8);
-  const fn = `write${type || 'UInt8'}`;
+  const fn = `write${type}`;
 
   if (!/\d/.test(fn))
     benchSpecialInt(buff, fn, n);
diff --git a/benchmark/buffers/dataview-set.js b/benchmark/buffers/dataview-set.js
index a741d11356ea32..b7914fe45f175b 100644
--- a/benchmark/buffers/dataview-set.js
+++ b/benchmark/buffers/dataview-set.js
@@ -40,7 +40,6 @@ const mod = {
 };
 
 function main({ n, type }) {
-  type = type || 'Uint8';
   const ab = new ArrayBuffer(8);
   const dv = new DataView(ab, 0, 8);
   const le = /LE$/.test(type);
diff --git a/benchmark/crypto/aes-gcm-throughput.js b/benchmark/crypto/aes-gcm-throughput.js
index b1b08c481700ea..3f2b9ba45eb3f2 100644
--- a/benchmark/crypto/aes-gcm-throughput.js
+++ b/benchmark/crypto/aes-gcm-throughput.js
@@ -9,9 +9,6 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ n, len, cipher }) {
-  // Default cipher for tests.
-  if (cipher === '')
-    cipher = 'aes-128-gcm';
   const message = Buffer.alloc(len, 'b');
   const key = crypto.randomBytes(keylen[cipher]);
   const iv = crypto.randomBytes(12);
diff --git a/benchmark/crypto/cipher-stream.js b/benchmark/crypto/cipher-stream.js
index 9f4a1bb4fa3d40..47a8931a540447 100644
--- a/benchmark/crypto/cipher-stream.js
+++ b/benchmark/crypto/cipher-stream.js
@@ -3,7 +3,7 @@ const common = require('../common.js');
 
 const bench = common.createBenchmark(main, {
   writes: [500],
-  cipher: [ 'AES192', 'AES256' ],
+  cipher: ['AES192', 'AES256'],
   type: ['asc', 'utf', 'buf'],
   len: [2, 1024, 102400, 1024 * 1024],
   api: ['legacy', 'stream']
@@ -12,9 +12,6 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ api, cipher, type, len, writes }) {
-  // Default cipher for tests.
-  if (cipher === '')
-    cipher = 'AES192';
   if (api === 'stream' && /^v0\.[0-8]\./.test(process.version)) {
     console.error('Crypto streams not available until v0.10');
     // Use the legacy, just so that we can compare them.
@@ -29,7 +26,6 @@ function main({ api, cipher, type, len, writes }) {
   alice.generateKeys();
   bob.generateKeys();
 
-
   const pubEnc = /^v0\.[0-8]/.test(process.version) ? 'binary' : null;
   const alice_secret = alice.computeSecret(bob.getPublicKey(), pubEnc, 'hex');
   const bob_secret = bob.computeSecret(alice.getPublicKey(), pubEnc, 'hex');
diff --git a/benchmark/es/defaultparams-bench.js b/benchmark/es/defaultparams-bench.js
index ab9cc45749c996..fde4cb11ad448a 100644
--- a/benchmark/es/defaultparams-bench.js
+++ b/benchmark/es/defaultparams-bench.js
@@ -36,8 +36,6 @@ function runDefaultParams(n) {
 
 function main({ n, method }) {
   switch (method) {
-    case '':
-      // Empty string falls through to next line as default, mostly for tests.
     case 'withoutdefaults':
       runOldStyleDefaults(n);
       break;
diff --git a/benchmark/es/destructuring-bench.js b/benchmark/es/destructuring-bench.js
index f1b484bd47e08f..c07c0383da91ac 100644
--- a/benchmark/es/destructuring-bench.js
+++ b/benchmark/es/destructuring-bench.js
@@ -36,8 +36,6 @@ function runSwapDestructured(n) {
 
 function main({ n, method }) {
   switch (method) {
-    case '':
-      // Empty string falls through to next line as default, mostly for tests.
     case 'swap':
       runSwapManual(n);
       break;
diff --git a/benchmark/es/destructuring-object-bench.js b/benchmark/es/destructuring-object-bench.js
index 68dc17073badc2..29c83bd188e89d 100644
--- a/benchmark/es/destructuring-object-bench.js
+++ b/benchmark/es/destructuring-object-bench.js
@@ -33,8 +33,6 @@ function runDestructured(n) {
 
 function main({ n, method }) {
   switch (method) {
-    case '':
-      // Empty string falls through to next line as default, mostly for tests.
     case 'normal':
       runNormal(n);
       break;
diff --git a/benchmark/es/foreach-bench.js b/benchmark/es/foreach-bench.js
index 88bfed00fbc27c..6992a1a5749438 100644
--- a/benchmark/es/foreach-bench.js
+++ b/benchmark/es/foreach-bench.js
@@ -54,8 +54,6 @@ function main({ n, count, method }) {
     items[i] = i;
 
   switch (method) {
-    case '':
-      // Empty string falls through to next line as default, mostly for tests.
     case 'for':
       fn = useFor;
       break;
diff --git a/benchmark/es/map-bench.js b/benchmark/es/map-bench.js
index 1b3ba4789db073..d0b8534cf7c906 100644
--- a/benchmark/es/map-bench.js
+++ b/benchmark/es/map-bench.js
@@ -104,8 +104,6 @@ function runMap(n) {
 
 function main({ n, method }) {
   switch (method) {
-    case '':
-      // Empty string falls through to next line as default, mostly for tests.
     case 'object':
       runObject(n);
       break;
diff --git a/benchmark/es/restparams-bench.js b/benchmark/es/restparams-bench.js
index d568e28744541f..8129bc92533332 100644
--- a/benchmark/es/restparams-bench.js
+++ b/benchmark/es/restparams-bench.js
@@ -51,8 +51,6 @@ function runUseArguments(n) {
 function main({ n, method }) {
   let fn;
   switch (method) {
-    case '':
-      // Empty string falls through to next line as default, mostly for tests.
     case 'copy':
       fn = runCopyArguments;
       break;
diff --git a/benchmark/es/spread-assign.js b/benchmark/es/spread-assign.js
index 97a5c5458e396b..970512aa6b93d4 100644
--- a/benchmark/es/spread-assign.js
+++ b/benchmark/es/spread-assign.js
@@ -18,8 +18,6 @@ function main({ n, context, count, rest, method }) {
   let obj;  // eslint-disable-line no-unused-vars
 
   switch (method) {
-    case '':
-      // Empty string falls through to next line as default, mostly for tests.
     case '_extend':
       bench.start();
       for (let i = 0; i < n; i++)
diff --git a/benchmark/es/spread-bench.js b/benchmark/es/spread-bench.js
index fc56c9433f2add..ae5b4abbb99c02 100644
--- a/benchmark/es/spread-bench.js
+++ b/benchmark/es/spread-bench.js
@@ -32,8 +32,6 @@ function main({ n, context, count, rest, method }) {
     args[i] = i;
 
   switch (method) {
-    case '':
-      // Empty string falls through to next line as default, mostly for tests.
     case 'apply':
       bench.start();
       for (let i = 0; i < n; i++)
diff --git a/benchmark/es/string-concatenations.js b/benchmark/es/string-concatenations.js
index 72fb7f9969b604..3c0b27e05019d1 100644
--- a/benchmark/es/string-concatenations.js
+++ b/benchmark/es/string-concatenations.js
@@ -23,8 +23,6 @@ function main({ n, mode }) {
   let string;
 
   switch (mode) {
-    case '':
-      // Empty string falls through to next line as default, mostly for tests.
     case 'multi-concat':
       bench.start();
       for (let i = 0; i < n; i++)
diff --git a/benchmark/es/string-repeat.js b/benchmark/es/string-repeat.js
index 9e33e4acf47118..f4bd616e4ada4b 100644
--- a/benchmark/es/string-repeat.js
+++ b/benchmark/es/string-repeat.js
@@ -18,8 +18,6 @@ function main({ n, size, encoding, mode }) {
   let str;
 
   switch (mode) {
-    case '':
-      // Empty string falls through to next line as default, mostly for tests.
     case 'Array':
       bench.start();
       for (let i = 0; i < n; i++)
diff --git a/benchmark/misc/arguments.js b/benchmark/misc/arguments.js
index 8fefe617a51d56..39f4020b1ad20e 100644
--- a/benchmark/misc/arguments.js
+++ b/benchmark/misc/arguments.js
@@ -34,8 +34,6 @@ function usingPredefined() {
 function main({ n, method, args }) {
   let fn;
   switch (method) {
-    // '' is a default case for tests
-    case '':
     case 'restAndSpread':
       fn = usingRestAndSpread;
       break;
diff --git a/benchmark/misc/getstringwidth.js b/benchmark/misc/getstringwidth.js
index c10f7af8483cf9..9dd4b47df7182e 100644
--- a/benchmark/misc/getstringwidth.js
+++ b/benchmark/misc/getstringwidth.js
@@ -10,8 +10,6 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ n, type }) {
-  // Default value for testing purposes.
-  type = type || 'ascii';
   const { getStringWidth } = require('internal/util/inspect');
 
   const str = ({
diff --git a/benchmark/misc/object-property-bench.js b/benchmark/misc/object-property-bench.js
index 0a4d004999ed23..9b33ac9a636889 100644
--- a/benchmark/misc/object-property-bench.js
+++ b/benchmark/misc/object-property-bench.js
@@ -64,8 +64,6 @@ function runSymbol(n) {
 function main({ n, method }) {
 
   switch (method) {
-    // '' is a default case for tests
-    case '':
     case 'property':
       runProperty(n);
       break;
diff --git a/benchmark/misc/punycode.js b/benchmark/misc/punycode.js
index 5f85df758ef7e3..9c674b5deefb8c 100644
--- a/benchmark/misc/punycode.js
+++ b/benchmark/misc/punycode.js
@@ -62,8 +62,6 @@ function runICU(n, val) {
 
 function main({ n, val, method }) {
   switch (method) {
-    // '' is a default case for tests
-    case '':
     case 'punycode':
       runPunycode(n, val);
       break;
diff --git a/benchmark/misc/trace.js b/benchmark/misc/trace.js
index f06e8597cc30e9..8620e99329b224 100644
--- a/benchmark/misc/trace.js
+++ b/benchmark/misc/trace.js
@@ -41,7 +41,6 @@ function main({ n, method }) {
   } = common.binding('trace_events');
 
   switch (method) {
-    case '':
     case 'trace':
       doTrace(n, trace);
       break;
diff --git a/benchmark/misc/util-extend-vs-object-assign.js b/benchmark/misc/util-extend-vs-object-assign.js
index b3d95f0e2d97a4..83aec7b9c82231 100644
--- a/benchmark/misc/util-extend-vs-object-assign.js
+++ b/benchmark/misc/util-extend-vs-object-assign.js
@@ -9,10 +9,6 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ n, type }) {
-  // Default value for tests.
-  if (type === '')
-    type = 'extend';
-
   let fn;
   if (type === 'extend') {
     fn = util._extend;
diff --git a/benchmark/url/url-format.js b/benchmark/url/url-format.js
index 3e91cefd363c37..be5632d2b67367 100644
--- a/benchmark/url/url-format.js
+++ b/benchmark/url/url-format.js
@@ -13,7 +13,7 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ type, n }) {
-  const input = inputs[type] || '';
+  const input = inputs[type];
 
   // Force-optimize url.format() so that the benchmark doesn't get
   // disrupted by the optimizer kicking in halfway through.
diff --git a/benchmark/url/url-parse.js b/benchmark/url/url-parse.js
index 751a11201b11e2..b3e83188b2192f 100644
--- a/benchmark/url/url-parse.js
+++ b/benchmark/url/url-parse.js
@@ -13,7 +13,7 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ type, n }) {
-  const input = inputs[type] || '';
+  const input = inputs[type];
 
   bench.start();
   for (let i = 0; i < n; i += 1)
diff --git a/benchmark/util/format.js b/benchmark/util/format.js
index 976e0f4e655486..f7a6caa81c96b6 100644
--- a/benchmark/util/format.js
+++ b/benchmark/util/format.js
@@ -23,8 +23,7 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ n, type }) {
-  // For testing, if supplied with an empty type, default to string.
-  const [first, second] = inputs[type || 'string'];
+  const [first, second] = inputs[type];
 
   bench.start();
   for (let i = 0; i < n; i++) {
diff --git a/benchmark/util/inspect-array.js b/benchmark/util/inspect-array.js
index 4fd73785f789d1..987b40479184d2 100644
--- a/benchmark/util/inspect-array.js
+++ b/benchmark/util/inspect-array.js
@@ -23,8 +23,6 @@ function main({ n, len, type }) {
       opts = { showHidden: true };
       arr = arr.fill('denseArray');
       break;
-      // For testing, if supplied with an empty type, default to denseArray.
-    case '':
     case 'denseArray':
       arr = arr.fill('denseArray');
       break;
diff --git a/benchmark/util/type-check.js b/benchmark/util/type-check.js
index 8d57bc000afcd1..792f61cf6fb217 100644
--- a/benchmark/util/type-check.js
+++ b/benchmark/util/type-check.js
@@ -35,9 +35,6 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ type, argument, version, n }) {
-  // For testing, if supplied with an empty type, default to ArrayBufferView.
-  type = type || 'ArrayBufferView';
-
   const util = common.binding('util');
   const types = require('internal/util/types');