From 7c82f4804604a12c1efa1c688110dc6aeead2ab0 Mon Sep 17 00:00:00 2001
From: Seebs <seebs@seebs.net>
Date: Tue, 13 Nov 2018 14:06:15 -0600
Subject: [PATCH] improve testing for intersections of array/array pairs

A transient bug introduced in intersectionCountArrayArray was
not caught by the tests, because it would only manifest when
two containers of different lengths were being compared. Also
improve the testing for intersectArrayArray, even though that
code hasn't been changed.
---
 roaring/roaring_test.go | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/roaring/roaring_test.go b/roaring/roaring_test.go
index 6c31b7701..f5c016ea3 100644
--- a/roaring/roaring_test.go
+++ b/roaring/roaring_test.go
@@ -411,13 +411,29 @@ func TestBitmap_Intersection_Empty(t *testing.T) {
 }
 
 func TestBitmap_IntersectArrayArray(t *testing.T) {
-	bm0 := roaring.NewFileBitmap(0, 1, 2683, 5005)
+	bm0 := roaring.NewFileBitmap(0, 1, 7, 9, 11, 2683, 5005)
 	bm1 := roaring.NewFileBitmap(0, 2683, 2684, 5000)
+	expected := []uint64{0, 2683}
 
 	result := bm0.Intersect(bm1)
 	if n := result.Count(); n != 2 {
 		t.Fatalf("unexpected n: %d", n)
 	}
+	for _, e := range expected {
+		if !result.Contains(e) {
+			t.Fatalf("missing value %d", e)
+		}
+	}
+	// confirm that it also works going the other way
+	result = bm1.Intersect(bm0)
+	if n := result.Count(); n != 2 {
+		t.Fatalf("unexpected n: %d", n)
+	}
+	for _, e := range expected {
+		if !result.Contains(e) {
+			t.Fatalf("missing value %d", e)
+		}
+	}
 }
 
 func TestBitmap_IntersectBitmapBitmap(t *testing.T) {
@@ -689,10 +705,10 @@ func TestBitmap_Flip_After(t *testing.T) {
 
 }
 
-// Ensure bitmap can return the number of intersecting bits in two bitmaps.
+// Ensure bitmap can return the number of intersecting bits in two arrays.
 func TestBitmap_IntersectionCount_ArrayArray(t *testing.T) {
-	bm0 := roaring.NewFileBitmap(0, 1, 1000001, 1000002, 1000003)
-	bm1 := roaring.NewFileBitmap(0, 50000, 1000001, 1000002)
+	bm0 := roaring.NewFileBitmap(0, 1000001, 1000002, 1000003)
+	bm1 := roaring.NewFileBitmap(0, 50000, 999998, 999999, 1000000, 1000001, 1000002)
 
 	if n := bm0.IntersectionCount(bm1); n != 3 {
 		t.Fatalf("unexpected n: %d", n)