more test coverage

config.go

@@ -52,6 +52,9 @@ func (c *Config) ValidPrime() error {
 	if !c.Prime.ProbablyPrime(0) {
 		return ErrConfigInvalidPrime
 	}
+	if len(c.Prime.Bytes()) < 2 {
+		return ErrConfigInvalidPrime
+	}
 	return nil
 }
 

config_test.go

@@ -17,9 +17,69 @@ func Test_prepare(t *testing.T) {
 	if c.Prime.Cmp(newPrime) != 0 {
 		t.Errorf("expected %v, got %v", newPrime, c.Prime)
 	}
+	if err := c.ValidPrime(); err == nil {
+		t.Errorf("expected error, got nil")
+	}
+	c.Prime = DefaultPrime
+	if err := c.ValidPrime(); err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	c.Prime = nil
+	if err := c.ValidPrime(); err == nil {
+		t.Errorf("expected error, got nil")
+	}
+}
+
+func TestValidPrime(t *testing.T) {
+	c := Config{}
+	c.prepare()
+	if err := c.ValidPrime(); err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	c.Prime = nil
+	if err := c.ValidPrime(); err == nil {
+		t.Errorf("expected error, got nil")
+	}
+	c.Prime = big.NewInt(1002)
+	if err := c.ValidPrime(); err == nil {
+		t.Errorf("expected error, got nil")
+	}
+}
+
+func TestValidConfig(t *testing.T) {
+	c := Config{}
+	c.prepare()
+	if err := c.ValidConfig([]byte{}); err == nil {
+		t.Errorf("expected error, got nil")
+	}
+	c.Shares = MinShares - 1
+	c.Min = MinMinShares
+	if err := c.ValidConfig([]byte{}); err == nil {
+		t.Errorf("expected error, got nil")
+	}
+	c.Shares = MinShares
+	c.Min = MinMinShares - 1
+	if err := c.ValidConfig([]byte{}); err == nil {
+		t.Errorf("expected error, got nil")
+	}
+	c.Shares = MinShares + 1
+	c.Min = MinMinShares - 1
+	if err := c.ValidConfig([]byte{}); err == nil {
+		t.Errorf("expected error, got nil")
+	}
+	c.Shares = MinShares
+	c.Min = MinMinShares
+	c.Prime = nil
+	if err := c.ValidConfig([]byte{}); err == nil {
+		t.Errorf("expected error, got nil")
+	}
+	c.Prime = new(big.Int).SetUint64(10007)
+	if err := c.ValidConfig([]byte("12345")); err == nil {
+		t.Errorf("expected error, got nil")
+	}
 }
 
-func Test_maxSecretPartSize(t *testing.T) {
+func TestMaxMessageLen(t *testing.T) {
 	c := Config{Prime: big.NewInt(13)}
 	if c.MaxMessageLen() != 0 {
 		t.Errorf("expected 0, got %d", c.MaxMessageLen())

encode_test.go

@@ -1,6 +1,7 @@
 package gosss
 
 import (
+	"math/big"
 	"testing"
 )
 
@@ -32,4 +33,20 @@ func Test_shareToStrStrToShare(t *testing.T) {
 			t.Errorf("unexpected share: %s", y)
 		}
 	}
+	// test coords
+	invalidX, _ := new(big.Int).SetString("1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000", 10)
+	invalidY, _ := new(big.Int).SetString("1", 10)
+	_, err := shareToStr(invalidX, invalidY)
+	if err == nil {
+		t.Errorf("expected error, got nil")
+	}
+	// test invalid share
+	_, _, err = strToShare("3")
+	if err == nil {
+		t.Errorf("expected error, got nil")
+	}
+	_, _, err = strToShare("10")
+	if err == nil {
+		t.Errorf("expected error, got nil")
+	}
 }

sss.go

@@ -1,9 +1,6 @@
 package gosss
 
-import (
-	"fmt"
-	"math/big"
-)
+import "math/big"
 
 // HideMessage generates the shares of the message using the Shamir Secret
 // Sharing algorithm. It returns the shares as strings. The message is encoded
@@ -37,7 +34,7 @@ func HideMessage(message []byte, conf *Config) ([]string, error) {
 	for i := 0; i < len(xs); i++ {
 		share, err := shareToStr(xs[i], ys[i])
 		if err != nil {
-			return nil, fmt.Errorf("error encoding shares: %w", err)
+			return nil, err
 		}
 		shares = append(shares, share)
 	}
@@ -69,7 +66,7 @@ func RecoverMessage(inputs []string, conf *Config) ([]byte, error) {
 	for _, input := range inputs {
 		x, y, err := strToShare(input)
 		if err != nil {
-			return nil, fmt.Errorf("error decoding shares: %w", err)
+			return nil, err
 		}
 		xs = append(xs, x)
 		ys = append(ys, y)