iden3 · vmidyllic · May 19, 2022 · May 12, 2022
diff --git a/claim.go b/claim.go
@@ -59,6 +59,9 @@ var ErrIncorrectIDPosition = errors.New("incorrect ID position")
 // ErrNoID returns when ID not found in the Claim.
 var ErrNoID = errors.New("ID is not set")
 
+// ErrInvalidSubjectPosition returns when subject position flags sets in invalid value.
+var ErrInvalidSubjectPosition = errors.New("invalid subject position")
+
 // ErrSlotOverflow means some ElemBytes overflows Q Field. And wraps the name
 // of overflowed slot.
 type ErrSlotOverflow struct {
@@ -69,6 +72,7 @@ func (e ErrSlotOverflow) Error() string {
 	return fmt.Sprintf("Slot %v not in field (too large)", e.Field)
 }
 
+
 type SlotName string
 
 const (
@@ -324,14 +328,16 @@ func (c *Claim) GetSchemaHash() SchemaHash {
 }
 
 // GetIDPosition returns the position at which the ID is stored.
-func (c *Claim) GetIDPosition() IDPosition {
+func (c *Claim) GetIDPosition() (IDPosition, error) {
 	switch c.getSubject() {
+	case subjectFlagSelf:
+		return IDPositionNone, nil
 	case subjectFlagOtherIdenIndex:
-		return IDPositionIndex
+		return IDPositionIndex, nil
 	case subjectFlagOtherIdenValue:
-		return IDPositionValue
+		return IDPositionValue, nil
 	default:
-		return IDPositionNone
+		return 0, ErrInvalidSubjectPosition
 	}
 }
 

diff --git a/claim_test.go b/claim_test.go
@@ -405,3 +405,90 @@ func TestSchemaHash_BigInt(t *testing.T) {
 	assert.Equal(t, exp, got)
 
 }
+
+func TestGetIDPosition(t *testing.T) {
+	tests := []struct {
+		name             string
+		claim            func(t *testing.T) *Claim
+		expectedPosition IDPosition
+	}{
+		{
+			name: "self claim",
+			claim: func(t *testing.T) *Claim {
+				c, err := NewClaim(SchemaHash{})
+				require.NoError(t, err)
+				return c
+			},
+			expectedPosition: IDPositionNone,
+		},
+		{
+			name: "subject stored in index",
+			claim: func(t *testing.T) *Claim {
+				c, err := NewClaim(SchemaHash{})
+				require.NoError(t, err)
+
+				var genesis [27]byte
+				genesis32bytes := hashBytes([]byte("genesistest"))
+				copy(genesis[:], genesis32bytes[:])
+
+				c.SetIndexID(NewID(TypeDefault, genesis))
+				return c
+			},
+			expectedPosition: IDPositionIndex,
+		},
+		{
+			name: "subject stored in value",
+			claim: func(t *testing.T) *Claim {
+				c, err := NewClaim(SchemaHash{})
+				require.NoError(t, err)
+
+				var genesis [27]byte
+				genesis32bytes := hashBytes([]byte("genesistest"))
+				copy(genesis[:], genesis32bytes[:])
+
+				c.SetValueID(NewID(TypeDefault, genesis))
+				return c
+			},
+			expectedPosition: IDPositionValue,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			c := tt.claim(t)
+			position, err := c.GetIDPosition()
+			require.NoError(t, err)
+			require.Equal(t, tt.expectedPosition, position)
+		})
+	}
+}
+
+func TestGetIDPosition_ErrorCase(t *testing.T) {
+	tests := []struct {
+		name             string
+		claim            func(t *testing.T) *Claim
+		expectedPosition IDPosition
+		expectedError error
+	}{
+		{
+			name: "invalid position",
+			claim: func(t *testing.T) *Claim {
+				c, err := NewClaim(SchemaHash{})
+				require.NoError(t, err)
+				c.setSubject(_subjectFlagInvalid)
+				return c
+			},
+			expectedPosition: IDPositionNone,
+			expectedError: ErrInvalidSubjectPosition,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			c := tt.claim(t)
+			position, err := c.GetIDPosition()
+			require.ErrorIs(t, err, tt.expectedError)
+			require.Equal(t, tt.expectedPosition, position)
+		})
+	}
+}