initial release
diff --git a/re2/testing/string_generator_test.cc b/re2/testing/string_generator_test.cc
new file mode 100644
index 0000000..d13401a
--- /dev/null
+++ b/re2/testing/string_generator_test.cc
@@ -0,0 +1,109 @@
+// Copyright 2008 The RE2 Authors. All Rights Reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test StringGenerator.
+
+#include <stdlib.h>
+#include <string>
+#include <vector>
+#include "util/test.h"
+#include "re2/testing/string_generator.h"
+#include "re2/testing/regexp_generator.h"
+
+namespace re2 {
+
+// Returns i to the e.
+static int64 IntegerPower(int i, int e) {
+ int64 p = 1;
+ while (e-- > 0)
+ p *= i;
+ return p;
+}
+
+// Checks that for given settings of the string generator:
+// * it generates strings that are non-decreasing in length.
+// * strings of the same length are sorted in alphabet order.
+// * it doesn't generate the same string twice.
+// * it generates the right number of strings.
+//
+// If all of these hold, the StringGenerator is behaving.
+// Assumes that the alphabet is sorted, so that the generated
+// strings can just be compared lexicographically.
+static void RunTest(int len, string alphabet, bool donull) {
+ StringGenerator g(len, Explode(alphabet));
+
+ int n = 0;
+ int last_l = -1;
+ string last_s;
+
+ if (donull) {
+ g.GenerateNULL();
+ EXPECT_TRUE(g.HasNext());
+ StringPiece sp = g.Next();
+ EXPECT_EQ(sp.data(), static_cast<const char*>(NULL));
+ EXPECT_EQ(sp.size(), 0);
+ }
+
+ while (g.HasNext()) {
+ string s = g.Next().as_string();
+ n++;
+
+ // Check that all characters in s appear in alphabet.
+ for (const char *p = s.c_str(); *p != '\0'; ) {
+ Rune r;
+ p += chartorune(&r, p);
+ EXPECT_TRUE(utfrune(alphabet.c_str(), r) != NULL);
+ }
+
+ // Check that string is properly ordered w.r.t. previous string.
+ int l = utflen(s.c_str());
+ EXPECT_LE(l, len);
+ if (last_l < l) {
+ last_l = l;
+ } else {
+ EXPECT_EQ(last_l, l);
+ EXPECT_LT(last_s, s);
+ }
+ last_s = s;
+ }
+
+ // Check total string count.
+ int64 m = 0;
+ int alpha = utflen(alphabet.c_str());
+ if (alpha == 0) // Degenerate case.
+ len = 0;
+ for (int i = 0; i <= len; i++)
+ m += IntegerPower(alpha, i);
+ EXPECT_EQ(n, m);
+}
+
+TEST(StringGenerator, NoLength) {
+ RunTest(0, "abc", false);
+}
+
+TEST(StringGenerator, NoLengthNoAlphabet) {
+ RunTest(0, "", false);
+}
+
+TEST(StringGenerator, NoAlphabet) {
+ RunTest(5, "", false);
+}
+
+TEST(StringGenerator, Simple) {
+ RunTest(3, "abc", false);
+}
+
+TEST(StringGenerator, UTF8) {
+ RunTest(4, "abc\xE2\x98\xBA", false);
+}
+
+TEST(StringGenerator, GenNULL) {
+ RunTest(0, "abc", true);
+ RunTest(0, "", true);
+ RunTest(5, "", true);
+ RunTest(3, "abc", true);
+ RunTest(4, "abc\xE2\x98\xBA", true);
+}
+
+} // namespace re2
