Merge pull request #11 from risteli/sibling_slices

Fixes slices equality, when slices are extracted from the same array

deep.go

@@ -282,12 +282,13 @@ func (c *cmp) equals(a, b reflect.Value, level int) {
 			return
 		}
 
-		if a.Pointer() == b.Pointer() {
+		aLen := a.Len()
+		bLen := b.Len()
+
+		if a.Pointer() == b.Pointer() && aLen == bLen {
 			return
 		}
 
-		aLen := a.Len()
-		bLen := b.Len()
 		n := aLen
 		if bLen > aLen {
 			n = bLen

deep_test.go

@@ -611,6 +611,77 @@ func TestSlice(t *testing.T) {
 	}
 }
 
+func TestSiblingSlices(t *testing.T) {
+	father := []int{1, 2, 3, 4}
+	a := father[0:3]
+	b := father[0:3]
+
+	diff := deep.Equal(a, b)
+	if len(diff) > 0 {
+		t.Error("should be equal:", diff)
+	}
+	diff = deep.Equal(b, a)
+	if len(diff) > 0 {
+		t.Error("should be equal:", diff)
+	}
+
+	a = father[0:3]
+	b = father[0:2]
+	diff = deep.Equal(a, b)
+	if diff == nil {
+		t.Fatal("no diff")
+	}
+	if len(diff) != 1 {
+		t.Error("too many diff:", diff)
+	}
+	if diff[0] != "slice[2]: 3 != <no value>" {
+		t.Error("wrong diff:", diff[0])
+	}
+
+	a = father[0:2]
+	b = father[0:3]
+
+	diff = deep.Equal(a, b)
+	if diff == nil {
+		t.Fatal("no diff")
+	}
+	if len(diff) != 1 {
+		t.Error("too many diff:", diff)
+	}
+	if diff[0] != "slice[2]: <no value> != 3" {
+		t.Error("wrong diff:", diff[0])
+	}
+
+	a = father[0:2]
+	b = father[2:4]
+
+	diff = deep.Equal(a, b)
+	if diff == nil {
+		t.Fatal("no diff")
+	}
+	if len(diff) != 2 {
+		t.Error("too many diff:", diff)
+	}
+	if diff[0] != "slice[0]: 1 != 3" {
+		t.Error("wrong diff:", diff[0])
+	}
+	if diff[1] != "slice[1]: 2 != 4" {
+		t.Error("wrong diff:", diff[1])
+	}
+
+	a = father[0:0]
+	b = father[1:1]
+
+	diff = deep.Equal(a, b)
+	if len(diff) > 0 {
+		t.Error("should be equal:", diff)
+	}
+	diff = deep.Equal(b, a)
+	if len(diff) > 0 {
+		t.Error("should be equal:", diff)
+	}
+}
+
 func TestNilInterface(t *testing.T) {
 	type T struct{ i int }