more tests

iprange.go

@@ -234,17 +234,11 @@ func Merge(in []IPRange) (out []IPRange) {
 }
 
 func (a IPRange) isDisjunct(b IPRange) bool {
-	if a.last.Less(b.first) || b.last.Less(a.first) {
-		return true
-	}
-	return false
+	return a.last.Less(b.first) || b.last.Less(a.first)
 }
 
 func (a IPRange) covers(b IPRange) bool {
-	if a.first.Compare(b.first) <= 0 && a.last.Compare(b.last) >= 0 {
-		return true
-	}
-	return false
+	return a.first.Compare(b.first) <= 0 && a.last.Compare(b.last) >= 0
 }
 
 // Remove the slice of IPRanges from receiver, returns the remaining IPRanges.
@@ -268,23 +262,23 @@ func (r IPRange) Remove(in []IPRange) (out []IPRange) {
 		return []IPRange{r}
 	}
 
-	for _, d := range merged {
+	for _, m := range merged {
 		// case order is important!
 		switch {
-		case d.isDisjunct(r):
+		case m.isDisjunct(r):
 			// no-op
 			continue
-		case d.covers(r):
-			// d covers r, d masks the rest
+		case m.covers(r):
+			// m covers r, m masks the rest
 			return out
-		case d.first.Compare(r.first) <= 0:
+		case m.first.Compare(r.first) <= 0:
 			// left overlap, move cursor
-			r.first = d.last.Next()
-		case d.first.Compare(r.first) > 0:
+			r.first = m.last.Next()
+		case m.first.Compare(r.first) > 0:
 			// right overlap, save [r.first, d.first-1)
-			out = append(out, IPRange{r.first, d.first.Prev()})
+			out = append(out, IPRange{r.first, m.first.Prev()})
 			// new r, (d.last, r.last]
-			r.first = d.last.Next()
+			r.first = m.last.Next()
 		default:
 			panic("logic error")
 		}

iprange_test.go

@@ -168,6 +168,12 @@ func TestFromPrefix(t *testing.T) {
 			t.Fatalf("FromPrefix(%s), want: (%s, %s), got: (%s, %s)", tt.pfx, tt.first, tt.last, first, last)
 		}
 	}
+
+	// corner case
+	r, err := iprange.FromNetipPrefix(netip.Prefix{})
+	if r.IsValid() || err == nil {
+		t.Fatalf("FomPrefix() of invalid prefix, want: inavlid range and error, got: (%v, %v)", r, err)
+	}
 }
 
 func TestMerge(t *testing.T) {
@@ -294,13 +300,28 @@ func TestRemoveCornerCases(t *testing.T) {
 		t.Errorf("Remove(self), got %v, want nil", rs)
 	}
 
-	// disjunct
+	// disjunct after
 	r = mustParseIPRange("10.0.0.0/16")
 	rs = r.Remove([]iprange.IPRange{mustParseIPRange("::/0")})
 	if rs[0] != r {
 		t.Errorf("Remove(disjunct), got %v, want %v", rs, []iprange.IPRange{r})
 	}
 
+	// disjunct before
+	r = mustParseIPRange("::/0")
+	rs = r.Remove([]iprange.IPRange{mustParseIPRange("0.0.0.0/0")})
+	if rs[0] != r {
+		t.Errorf("Remove(disjunct), got %v, want %v", rs, []iprange.IPRange{r})
+	}
+
+	// disjunct in loop
+	r = mustParseIPRange("0.0.0.0/0")
+	rs = r.Remove([]iprange.IPRange{mustParseIPRange("0.0.0.0/1"), mustParseIPRange("::/0")})
+	wantRs := []iprange.IPRange{mustParseIPRange("128.0.0.0/1")}
+	if !reflect.DeepEqual(rs, wantRs) {
+		t.Errorf("Remove(...), got %v, want %v", rs, wantRs)
+	}
+
 	// covers
 	r = mustParseIPRange("10.0.0.0/16")
 	rs = r.Remove([]iprange.IPRange{mustParseIPRange("10.0.0.0/8")})
@@ -842,7 +863,7 @@ func TestCompareUpper(t *testing.T) {
 		}
 
 		got = tt.r2.CompareUpper(tt.r1)
-		if -1*got != tt.want {
+		if -1*(got) != tt.want {
 			t.Fatalf("(%s).CompareLower(%s), want: %v, got: %v\n", tt.r2, tt.r1, tt.want, -1*got)
 		}
 	}