revert back to getting random number in the [0,1) range

* for whatever reason, std::uniform_real_distribution doesn't
  allow a>b when specifying the [a,b) half-open range.  So we
  need to get a number from [0,1) and then do (1.0-unif) to
  convert to the (0,1] range that we want.
* extend the unit test with more initial numbers, and write
  it in a more compact way.

1 files changed, 25 insertions, 9 deletions

diff --git a/searchlib/src/tests/tensor/hnsw_index/hnsw_index_test.cpp b/searchlib/src/tests/tensor/hnsw_index/hnsw_index_test.cpp
index 04f2076121f..b49292463bd 100644
--- a/searchlib/src/tests/tensor/hnsw_index/hnsw_index_test.cpp
+++ b/searchlib/src/tests/tensor/hnsw_index/hnsw_index_test.cpp
@@ -521,15 +521,31 @@ TEST_F(HnswIndexTest, shrink_called_heuristic)
 TEST(LevelGeneratorTest, gives_various_levels)
 {
     InvLogLevelGenerator generator(4);
-    EXPECT_EQ(2u, generator.max_level());
-    EXPECT_EQ(1u, generator.max_level());
-    EXPECT_EQ(0u, generator.max_level());
-    EXPECT_EQ(1u, generator.max_level());
-    EXPECT_EQ(0u, generator.max_level());
-    EXPECT_EQ(1u, generator.max_level());
-    EXPECT_EQ(0u, generator.max_level());
-    EXPECT_EQ(0u, generator.max_level());
-    EXPECT_EQ(0u, generator.max_level());
+    std::vector<uint32_t> got_levels(16);
+    for (auto & v : got_levels) { v = generator.max_level(); }
+    EXPECT_EQ(got_levels, std::vector<uint32_t>({
+        2, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0
+    }));
+    for (auto & v : got_levels) { v = generator.max_level(); }
+    EXPECT_EQ(got_levels, std::vector<uint32_t>({
+        0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    }));
+    for (auto & v : got_levels) { v = generator.max_level(); }
+    EXPECT_EQ(got_levels, std::vector<uint32_t>({
+        0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 2, 0
+    }));
+    for (auto & v : got_levels) { v = generator.max_level(); }
+    EXPECT_EQ(got_levels, std::vector<uint32_t>({
+        0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1
+    }));
+    for (auto & v : got_levels) { v = generator.max_level(); }
+    EXPECT_EQ(got_levels, std::vector<uint32_t>({
+        0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 2
+    }));
+    for (auto & v : got_levels) { v = generator.max_level(); }
+    EXPECT_EQ(got_levels, std::vector<uint32_t>({
+        0, 1, 1, 0, 3, 1, 2, 0, 0, 1, 0, 0, 0, 0, 0, 0
+    }));
 
     uint32_t left = 1000000;
     std::vector<uint32_t> hist;