internal/runtime/maps: move tombstone test to swiss file

This test fails on GOEXPERIMENT=noswissmap as it is testing behavior
specific to swissmaps. Move it to map_swiss_test.go to skip it on
noswissmap.

We could also switch the test to use NewTestMap, which provides a
swissmap even in GOEXPERIMENT=noswissmap, but that is tedious to use and
noswissmap is going away soon anyway.

For #70886.

Cq-Include-Trybots: luci.golang.try:gotip-linux-amd64-longtest-noswissmap
Change-Id: I6a6a636c5ec72217d936cd01e9da36ae127ea2c5
Reviewed-on: https://go-review.googlesource.com/c/go/+/666437
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/internal/runtime/maps/map_swiss_test.go

@@ -210,3 +210,58 @@ func TestTableGroupCount(t *testing.T) {
 		}
 	})
 }
+
+func TestTombstoneGrow(t *testing.T) {
+	tableSizes := []int{16, 32, 64, 128, 256}
+	for _, tableSize := range tableSizes {
+		for _, load := range []string{"low", "mid", "high"} {
+			capacity := tableSize * 7 / 8
+			var initialElems int
+			switch load {
+			case "low":
+				initialElems = capacity / 8
+			case "mid":
+				initialElems = capacity / 2
+			case "high":
+				initialElems = capacity
+			}
+			t.Run(fmt.Sprintf("tableSize=%d/elems=%d/load=%0.3f", tableSize, initialElems, float64(initialElems)/float64(tableSize)), func(t *testing.T) {
+				allocs := testing.AllocsPerRun(1, func() {
+					// Fill the map with elements.
+					m := make(map[int]int, capacity)
+					for i := range initialElems {
+						m[i] = i
+					}
+
+					// This is the heart of our test.
+					// Loop over the map repeatedly, deleting a key then adding a not-yet-seen key
+					// while keeping the map at a ~constant number of elements (+/-1).
+					nextKey := initialElems
+					for range 100000 {
+						for k := range m {
+							delete(m, k)
+							break
+						}
+						m[nextKey] = nextKey
+						nextKey++
+						if len(m) != initialElems {
+							t.Fatal("len(m) should remain constant")
+						}
+					}
+				})
+
+				// The make has 4 allocs (map, directory, table, groups).
+				// Each growth has 2 allocs (table, groups).
+				// We allow two growths if we start full, 1 otherwise.
+				// Fail (somewhat arbitrarily) if there are more than that.
+				allowed := float64(4 + 1*2)
+				if initialElems == capacity {
+					allowed += 2
+				}
+				if allocs > allowed {
+					t.Fatalf("got %v allocations, allowed %v", allocs, allowed)
+				}
+			})
+		}
+	}
+}

src/internal/runtime/maps/map_test.go

@@ -699,58 +699,3 @@ func TestMapDeleteClear(t *testing.T) {
 		t.Errorf("Delete(%d) failed to clear element. got %d want 0", key, gotElem)
 	}
 }
-
-func TestTombstoneGrow(t *testing.T) {
-	tableSizes := []int{16, 32, 64, 128, 256}
-	for _, tableSize := range tableSizes {
-		for _, load := range []string{"low", "mid", "high"} {
-			capacity := tableSize * 7 / 8
-			var initialElems int
-			switch load {
-			case "low":
-				initialElems = capacity / 8
-			case "mid":
-				initialElems = capacity / 2
-			case "high":
-				initialElems = capacity
-			}
-			t.Run(fmt.Sprintf("tableSize=%d/elems=%d/load=%0.3f", tableSize, initialElems, float64(initialElems)/float64(tableSize)), func(t *testing.T) {
-				allocs := testing.AllocsPerRun(1, func() {
-					// Fill the map with elements.
-					m := make(map[int]int, capacity)
-					for i := range initialElems {
-						m[i] = i
-					}
-
-					// This is the heart of our test.
-					// Loop over the map repeatedly, deleting a key then adding a not-yet-seen key
-					// while keeping the map at a ~constant number of elements (+/-1).
-					nextKey := initialElems
-					for range 100000 {
-						for k := range m {
-							delete(m, k)
-							break
-						}
-						m[nextKey] = nextKey
-						nextKey++
-						if len(m) != initialElems {
-							t.Fatal("len(m) should remain constant")
-						}
-					}
-				})
-
-				// The make has 4 allocs (map, directory, table, groups).
-				// Each growth has 2 allocs (table, groups).
-				// We allow two growths if we start full, 1 otherwise.
-				// Fail (somewhat arbitrarily) if there are more than that.
-				allowed := float64(4 + 1*2)
-				if initialElems == capacity {
-					allowed += 2
-				}
-				if allocs > allowed {
-					t.Fatalf("got %v allocations, allowed %v", allocs, allowed)
-				}
-			})
-		}
-	}
-}