From d1a9c91a96df1a208e8a7f1450743e73ebc75a81 Mon Sep 17 00:00:00 2001
From: Seebs <seebs@seebs.net>
Date: Mon, 25 Jan 2021 14:41:05 -0600
Subject: [PATCH] Test CountRange on non-container ranges.

This test was supposed to check against all the container types,
but especially bitmaps, but turns out not to work because the
containers turn into RLE containers. Oops. Now, we start with
every-other-bit for the first 8k, then start filling in the holes,
so we get some bitmap containers and then start generating
RLE containers.
---
 tx_internal_test.go | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/tx_internal_test.go b/tx_internal_test.go
index a5da9cccd..3ff4ddd63 100644
--- a/tx_internal_test.go
+++ b/tx_internal_test.go
@@ -37,20 +37,29 @@ func requireCountRangeSampleData(tb testing.TB) (*fragment, Tx) {
 		// request that each container get its own copy of the bitmap.
 		var bitmapSample [1025]uint64
 		for i := range arraySample {
-			arraySample[i] = uint16(i)
+			arraySample[i] = uint16(i * 2)
 		}
-		for i := 0; i < 4096/64; i++ {
-			bitmapSample[i] = ^uint64(0)
+		// Put corresponding bits in the bitmap...
+		for i := 0; i < 4096/32; i++ {
+			// bit 0 is 0x1, bit 2 is 0x4, so even-numbered bits
+			// are 0x5555....
+			bitmapSample[i] = 0x5555555555555555
 		}
 		bm := roaring.NewSliceBitmap()
 		for n := 0; n < 4096 && n < countRangeMaxN; n++ {
 			c := roaring.NewContainerArray(arraySample[:n])
 			bm.Put(uint64(n), c)
 		}
-		for n := 4096; n < countRangeMaxN; n++ {
+		// Start filling in the missing bits. This starts us out with
+		// bitmap containers, but then eventually converts to things
+		// that are more likely to be run containers. At the end of this,
+		// we should have exactly the first 8,192 bits set, for a single
+		// run of 8k.
+		for n := 4096; n < 8192; n++ {
 			c := roaring.NewContainerBitmapN(bitmapSample[:], int32(n))
 			bm.Put(uint64(n), c)
-			bitmapSample[n/64] |= 1 << (n % 64)
+			w := n - 4096
+			bitmapSample[w/32] |= 1 << (((n % 32) * 2) + 1)
 		}
 		var asBytes bytes.Buffer
 		n, err := bm.WriteTo(&asBytes)
@@ -90,11 +99,14 @@ func TestTx_CountRange(t *testing.T) {
 	expected := uint64(0)
 	j := uint64(0)
 	for i := uint64(0); i < countRangeMaxN; i += 7 {
+		expected += i
 		if i%4 == 3 {
 			expected -= (j * 7) + 21
 			j += 7
 		}
-		got, err := tx.CountRange("i", "f", viewStandard, 0, uint64(j)<<16, uint64(i)<<16)
+		// Every other bit gets set, for a total of i bits in container
+		// i, so they're all in the first (i*2) bits of the container.
+		got, err := tx.CountRange("i", "f", viewStandard, 0, uint64(j)<<16, (uint64(i)<<16)+(i*2))
 		if err != nil {
 			t.Fatalf("counting range: %v", err)
 		}
@@ -102,7 +114,8 @@ func TestTx_CountRange(t *testing.T) {
 			t.Fatalf("counting from container %d to %d, expected %d, got %d",
 				j, i, expected, got)
 		}
-		expected += (i * 7) + 21
+		// The -i here undoes the +i at the top of this loop.
+		expected += (i * 7) + 21 - i
 	}
 }