models: add tests for point construction

These tests check that NewPoint and NewPointFromBytes return an error if:

* arguments specify a point with no fields
* arguments specify a point with a field that has an empty name

These tests also check that Point.Fields() always returns, even in the presence
of corrupt binary data read with NewPointFromBytes.

These tests fail at this commit and are fixed by a subsequent commit.

Signed-off-by: Jon Seymour <jon@wildducktheories.com>

models/points_test.go

@@ -1772,3 +1772,27 @@ t159,label=another a=2i,value=1i 1`
 		t.Fatalf("expected 2 points, got %d", len(points))
 	}
 }
+
+func TestNewPointsWithBytesWithCorruptData(t *testing.T) {
+	ch := make(chan error)
+	go func() {
+		corrupted := []byte{0, 0, 0, 3, 102, 111, 111, 0, 0, 0, 4, 61, 34, 65, 34, 1, 0, 0, 0, 14, 206, 86, 119, 24, 32, 72, 233, 168, 2, 148}
+		p, err := models.NewPointFromBytes(corrupted)
+		p.Fields() // this method should always return, even if the data is corrupt.
+		ch <- err
+	}()
+	select {
+	case err := <-ch:
+		if err != nil {
+			t.Fatalf("unexpected error: got: %v, expected: nil", err)
+		}
+	case _ = <-time.NewTimer(time.Second).C:
+		t.Fatalf("probable infite loop. got: timeout, expected: return")
+	}
+}
+
+func TestNewPointsRejectsEmptyFieldNames(t *testing.T) {
+	if _, err := models.NewPoint("foo", nil, models.Fields{"": 1}, time.Now()); err == nil {
+		t.Fatalf("new point with empty field name. got: nil, expected: error")
+	}
+}