util: improve util inspect output

lib/internal/util/inspect.js

@@ -848,26 +848,27 @@ function groupArrayElements(ctx, output) {
   let totalLength = 0;
   let maxLength = 0;
   let i = 0;
+  const separatorSpace = 2; // Add 1 for the space and 1 for the separator.
   const dataLen = new Array(output.length);
   // Calculate the total length of all output entries and the individual max
   // entries length of all output entries. We have to remove colors first,
   // otherwise the length would not be calculated properly.
   for (; i < output.length; i++) {
     const len = ctx.colors ? removeColors(output[i]).length : output[i].length;
     dataLen[i] = len;
-    totalLength += len;
+    totalLength += len + separatorSpace;
     if (maxLength < len)
       maxLength = len;
   }
   // Add two to `maxLength` as we add a single whitespace character plus a comma
   // in-between two entries.
-  const actualMax = maxLength + 2;
+  const actualMax = maxLength + separatorSpace;
   // Check if at least three entries fit next to each other and prevent grouping
   // of arrays that contains entries of very different length (i.e., if a single
   // entry is longer than 1/5 of all other entries combined). Otherwise the
   // space in-between small entries would be enormous.
   if (actualMax * 3 + ctx.indentationLvl < ctx.breakLength &&
-      (totalLength / maxLength > 5 || maxLength <= 6)) {
+      (totalLength / actualMax > 5 || maxLength <= 6)) {
 
     const approxCharHeights = 2.5;
     const bias = 1;
@@ -1314,7 +1315,7 @@ function formatProperty(ctx, value, recurseTimes, key, type) {
   return `${name}:${extra}${str}`;
 }
 
-function isBelowBreakLength(ctx, output, start) {
+function isBelowBreakLength(ctx, output, start, base) {
   // Each entry is separated by at least a comma. Thus, we start with a total
   // length of at least `output.length`. In addition, some cases have a
   // whitespace in-between each other that is added to the total as well.
@@ -1331,7 +1332,8 @@ function isBelowBreakLength(ctx, output, start) {
       return false;
     }
   }
-  return true;
+  // Do not line up properties on the same line if `base` contains line breaks.
+  return base === '' || !base.includes('\n');
 }
 
 function reduceToSingleString(ctx, output, base, braces, combine = false) {
@@ -1342,7 +1344,7 @@ function reduceToSingleString(ctx, output, base, braces, combine = false) {
       // that may reduce `breakLength`.
       const start = output.length + ctx.indentationLvl +
                     braces[0].length + base.length + 10;
-      if (isBelowBreakLength(ctx, output, start)) {
+      if (isBelowBreakLength(ctx, output, start, base)) {
         return `${base ? `${base} ` : ''}${braces[0]} ${join(output, ', ')} ` +
           braces[1];
       }
@@ -1354,7 +1356,7 @@ function reduceToSingleString(ctx, output, base, braces, combine = false) {
   }
   // Line up all entries on a single line in case the entries do not exceed
   // `breakLength`.
-  if (isBelowBreakLength(ctx, output, 0)) {
+  if (isBelowBreakLength(ctx, output, 0, base)) {
     return `${braces[0]}${base ? ` ${base}` : ''} ${join(output, ', ')} ` +
       braces[1];
   }

test/parallel/test-repl-pretty-stack.js

@@ -48,12 +48,12 @@ const tests = [
   {
     command: '(() => { const err = Error(\'Whoops!\'); ' +
              'err.foo = \'bar\'; throw err; })()',
-    expected: 'Thrown:\n{ Error: Whoops!\n    at repl:1:22 foo: \'bar\' }\n',
+    expected: 'Thrown:\n{ Error: Whoops!\n    at repl:1:22\n  foo: \'bar\' }\n',
   },
   {
     command: '(() => { const err = Error(\'Whoops!\'); ' +
              'err.foo = \'bar\'; throw err; })()',
-    expected: 'Thrown:\n{ Error: Whoops!\n    at repl:1:22 foo: ' +
+    expected: 'Thrown:\n{ Error: Whoops!\n    at repl:1:22\n  foo: ' +
               "\u001b[32m'bar'\u001b[39m }\n",
     useColors: true
   },

test/parallel/test-repl.js

@@ -540,7 +540,9 @@ const errorTests = [
       /^    at .*/,
       /^    at .*/,
       /^    at .*/,
-      /^    at .*/
+      /^    at .*/,
+      "  code: 'MODULE_NOT_FOUND',",
+      "  requireStack: [ '<repl>' ] }"
     ]
   },
   // REPL should handle quotes within regexp literal in multiline mode

test/parallel/test-util-inspect.js

@@ -578,7 +578,7 @@ assert.strictEqual(util.inspect(-5e-324), '-5e-324');
   );
   assert.strictEqual(
     util.inspect(err2, { compact: true }),
-    '{ [Error: foo\nbar] bar: true }'
+    '{ [Error: foo\nbar]\n  bar: true }'
   );
   assert.strictEqual(
     util.inspect(err, { compact: true, breakLength: 5 }),
@@ -2099,6 +2099,30 @@ assert.strictEqual(
 
   assert.strictEqual(out, expected);
 
+  obj = [
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 1, 123456789
+  ];
+
+  out = util.inspect(obj, { compact: 3 });
+
+  expected = [
+    '[',
+    '  1,         1,         1,',
+    '  1,         1,         1,',
+    '  1,         1,         1,',
+    '  1,         1,         1,',
+    '  1,         1,         1,',
+    '  1,         1,         1,',
+    '  1,         1,         1,',
+    '  1,         1,         1,',
+    '  1,         1, 123456789',
+    ']'
+  ].join('\n');
+
+  assert.strictEqual(out, expected);
+
   // Verify that array grouping and line consolidation does not happen together.
   obj = {
     a: {