Fix indeterministic logging tests

Printing the content of hash-based containers doesn't lead always to the same string as their ordering is not fixed. Luckily the number of possible permutations is so small that we can enumerate all of them.

Fixes google#201.

src/stl_logging_unittest.cc

@@ -100,29 +100,42 @@ static void TestSTLLogging() {
 
 #ifdef GLOG_STL_LOGGING_FOR_EXT_HASH
   {
+    // hash_set doesn't have an ordering, so there are many options for the output.
+    vector<string> permutations{
+      "10 20 30", "10 30 20", "20 10 30", "20 30 10", "30 10 20", "30 20 10"
+    };
     // Test a hashed simple associative container.
     hash_set<int> hs;
     hs.insert(10);
     hs.insert(20);
     hs.insert(30);
     ostringstream ss;
     ss << hs;
-    EXPECT_EQ(ss.str(), "10 20 30");
+    EXPECT_TRUE(std::find(std::begin(permutations), std::end(permutations), ss.str()) != std::end(permutations));
     hash_set<int> copied_hs(hs);
     CHECK_EQ(hs, copied_hs);  // This must compile.
   }
 #endif
 
 #ifdef GLOG_STL_LOGGING_FOR_EXT_HASH
   {
+    // hash_set doesn't have an ordering, so there are many options for the output.
+    vector<string> permutations{
+      "(10, ten) (20, twenty) (30, thirty)",
+      "(10, ten) (30, thirty) (20, twenty)",
+      "(20, twenty) (10, ten) (30, thirty)",
+      "(20, twenty) (30, thirty) (10, ten)",
+      "(30, thirty) (10, ten) (20, twenty)",
+      "(30, thirty) (20, twenty) (10, ten)"
+    };
     // Test a hashed pair associative container.
     hash_map<int, string> hm;
     hm[10] = "ten";
     hm[20] = "twenty";
     hm[30] = "thirty";
     ostringstream ss;
     ss << hm;
-    EXPECT_EQ(ss.str(), "(10, ten) (20, twenty) (30, thirty)");
+    EXPECT_TRUE(std::find(std::begin(permutations), std::end(permutations), ss.str()) != std::end(permutations));
     hash_map<int, string> copied_hm(hm);
     CHECK_EQ(hm, copied_hm);  // this must compile
   }
@@ -162,6 +175,10 @@ static void TestSTLLogging() {
 
 #ifdef GLOG_STL_LOGGING_FOR_EXT_HASH
   {
+    // hash_set doesn't have an ordering, so there are many options for the output.
+    vector<string> permutations{
+      "10 20 30", "10 30 20", "20 10 30", "20 30 10", "30 10 20", "30 20 10"
+    };
     // Test a hashed simple associative container.
     // Use a user defined hash function.
     hash_set<int, user_hash> hs;
@@ -170,7 +187,7 @@ static void TestSTLLogging() {
     hs.insert(30);
     ostringstream ss;
     ss << hs;
-    EXPECT_EQ(ss.str(), "10 20 30");
+    EXPECT_TRUE(std::find(std::begin(permutations), std::end(permutations), ss.str()) != std::end(permutations));
     hash_set<int, user_hash> copied_hs(hs);
     CHECK_EQ(hs, copied_hs);  // This must compile.
   }