Add TestBigToCompact and TestCompactToBig (#1092)

* Add TestBigToCompact and TestCompactToBig

* Add tests

domain/consensus/utils/math/math_test.go

@@ -1,6 +1,8 @@
 package math
 
 import (
+	"math"
+	"math/big"
 	"testing"
 )
 
@@ -33,3 +35,60 @@ func TestFastLog2Floor(t *testing.T) {
 		}
 	}
 }
+
+// TestBigToCompact ensures BigToCompact converts big integers to the expected
+// compact representation.
+func TestBigToCompact(t *testing.T) {
+	tests := []struct {
+		in  string
+		out uint32
+	}{
+		{"0", 0},
+		{"-1", 25231360},
+		{"9223372036854775807", 142606335},
+		{"922337203685477580712312312123487", 237861256},
+	}
+
+	for x, test := range tests {
+		n := new(big.Int)
+		n.SetString(test.in, 10)
+		r := BigToCompact(n)
+		if r != test.out {
+			t.Errorf("TestBigToCompact test #%d failed: got %d want %d\n",
+				x, r, test.out)
+			return
+		}
+	}
+}
+
+// TestCompactToBig ensures CompactToBig converts numbers using the compact
+// representation to the expected big integers.
+func TestCompactToBig(t *testing.T) {
+	tests := []struct {
+		in  uint32
+		out string
+	}{
+		{0, "0"},
+		{10000000, "0"},
+		{math.MaxUint32, "-6311914495863998658485429352026283268468573753812676234178171506285465200675957" +
+			"87397376951158770808349115367298981082112562162319027637583517246275967980671962038665775867893645140" +
+			"22856089959012026469381002722748489975264028415685723882208353467651862351803217528553851158828320170" +
+			"89832330727351553686808317476632783024236208492771822246700842318520468733521003756809213629548010354" +
+			"33865968377930773213939300289069292503211567790599147939718451689002543278625341832829837474611074167" +
+			"86700705915281593002614032021233542099318559748885883681365573294332856023451874423425211080847063825" +
+			"199113186681992371681311588352",
+		},
+		{142606335, "9223370937343148032"},
+		{25231360, "-1"},
+		{237861256, "922337129789886856855791696084992"},
+	}
+
+	for i, test := range tests {
+		n := CompactToBig(test.in)
+		if n.String() != test.out {
+			t.Errorf("TestCompactToBig test #%d failed: got %s want %s",
+				i, n, test.out)
+			return
+		}
+	}
+}