Allow users to set the maximum length of array that the pretty-printer

will print out.

Currently, jasmine's pretty printer will iterate over an entire array,
formatting every element recursively. For very large arrays, this can
crash the page, or cause a 'slow script' warning.

This commit exposes a 'MAX_PRETTY_PRINT_ARRAY_LENGTH' option. If an
array larger than this is encountered, recursion will stop and the
array length will be printed instead e.g. "Array[20000000]".

The 'MAX_PRETTY_PRINT_ARRAY_LENGTH' option defaults to 100. This is
length of array will not kill your browser, but will allow you
to see big arrays, if you can stomach the output.

lib/jasmine-core/jasmine.js

@@ -101,6 +101,7 @@ getJasmineRequireObj().base = (function (jasmineGlobal) {
     };
 
     j$.MAX_PRETTY_PRINT_DEPTH = 40;
+    j$.MAX_PRETTY_PRINT_ARRAY_LENGTH = 100;
     j$.DEFAULT_TIMEOUT_INTERVAL = 5000;
 
     j$.getGlobal = function() {
@@ -1497,14 +1498,17 @@ getJasmineRequireObj().pp = function(j$) {
       this.append('Array');
       return;
     }
-
+    var length = Math.min(array.length, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
     this.append('[ ');
-    for (var i = 0; i < array.length; i++) {
+    for (var i = 0; i < length; i++) {
       if (i > 0) {
         this.append(', ');
       }
       this.format(array[i]);
     }
+    if(array.length > length){
+      this.append(', ...');
+    }
     this.append(' ]');
   };
 

spec/core/PrettyPrintSpec.js

@@ -70,6 +70,18 @@ describe("j$.pp", function () {
     expect(j$.pp(frozenObject)).toEqual("{ foo: { bar: 'baz' }, circular: <circular reference: Object> }");
   });
 
+  it("should truncate arrays that are longer than j$.MAX_PRETTY_PRINT_ARRAY_LENGTH", function() {
+    var originalMaxLength = j$.MAX_PRETTY_PRINT_ARRAY_LENGTH;
+    var array = [1, 2, 3];
+
+    try {
+      j$.MAX_PRETTY_PRINT_ARRAY_LENGTH = 2;
+      expect(j$.pp(array)).toEqual("[ 1, 2, ... ]");
+    } finally {
+      j$.MAX_PRETTY_PRINT_ARRAY_LENGTH = originalMaxLength;
+    }
+  });
+
   it("should stringify RegExp objects properly", function() {
     expect(j$.pp(/x|y|z/)).toEqual("/x|y|z/");
   });

src/core/PrettyPrinter.js

@@ -82,14 +82,17 @@ getJasmineRequireObj().pp = function(j$) {
       this.append('Array');
       return;
     }
-
+    var length = Math.min(array.length, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
     this.append('[ ');
-    for (var i = 0; i < array.length; i++) {
+    for (var i = 0; i < length; i++) {
       if (i > 0) {
         this.append(', ');
       }
       this.format(array[i]);
     }
+    if(array.length > length){
+      this.append(', ...');
+    }
     this.append(' ]');
   };
 

src/core/base.js

@@ -9,6 +9,7 @@ getJasmineRequireObj().base = (function (jasmineGlobal) {
     };
 
     j$.MAX_PRETTY_PRINT_DEPTH = 40;
+    j$.MAX_PRETTY_PRINT_ARRAY_LENGTH = 100;
     j$.DEFAULT_TIMEOUT_INTERVAL = 5000;
 
     j$.getGlobal = function() {