beacon: Improve Utils Coverage to 100% (#415)

beacon-chain/utils/checkbit_test.go

@@ -4,6 +4,33 @@ import (
 	"testing"
 )
 
+func TestCheckBit(t *testing.T) {
+	tests := []struct {
+		a []byte
+		b int
+		c bool
+	}{
+		{a: []byte{200}, b: 4, c: true},  //11001000
+		{a: []byte{148}, b: 5, c: true},  //10010100
+		{a: []byte{146}, b: 4, c: false}, //10010010
+		{a: []byte{179}, b: 7, c: true},  //10110011
+		{a: []byte{49}, b: 6, c: false},  //00110001
+
+	}
+	for _, tt := range tests {
+		set, err := CheckBit(tt.a, tt.b)
+		if err != nil {
+			t.Fatalf("Call check bit failed: %v", err)
+		}
+		if set != tt.c {
+			t.Errorf("Test check bit set failed with %v and location %v", tt.a, tt.b)
+		}
+	}
+	if _, err := CheckBit([]byte{1}, 8); err == nil {
+		t.Errorf("Call check bit should have failed with invalid index")
+	}
+}
+
 func TestBitSetCount(t *testing.T) {
 	tests := []struct {
 		a byte