add unit tests for truncate functions

Author: James Cor

sql/types/number.go

@@ -1482,19 +1482,21 @@ const (
 // TruncateStringToInt trims any whitespace from s, then truncates the string to the left most characters that make
 // up a valid integer. Empty strings are converted "0". Additionally, returns a flag indicating if truncation occurred.
 func TruncateStringToInt(s string) (string, bool) {
+	var seenDigit bool
 	s = strings.Trim(s, IntCutSet)
 	i, n := 0, len(s)
 	for ; i < n; i++ {
 		c := rune(s[i])
 		if unicode.IsDigit(c) {
+			seenDigit = true
 			continue
 		}
 		if i == 0 && (c == '-' || c == '+') {
 			continue
 		}
 		break
 	}
-	if i == 0 {
+	if !seenDigit {
 		return "0", i != n
 	}
 	return s[:i], i != n
@@ -1527,7 +1529,7 @@ func TruncateStringToDouble(s string) (string, bool) {
 		}
 		break
 	}
-	if i == 0 {
+	if !seenDigit {
 		return "0", i != n
 	}
 	return s[:i], i != n

sql/types/number_test.go

@@ -369,3 +369,204 @@ func TestNumberString(t *testing.T) {
 		})
 	}
 }
+
+func TestTruncateStringToInt(t *testing.T) {
+	tests := []struct {
+		input    string
+		exp      string
+		expTrunc bool
+	}{
+		{
+			input:    "1",
+			exp:      "1",
+			expTrunc: false,
+		},
+		{
+			// Whitespace does not count as truncation
+			input:    " \t   1 \t  ",
+			exp:      "1",
+			expTrunc: false,
+		},
+		{
+			// Newlines do count as part of truncation
+			input:    " \t\n1",
+			exp:      "0",
+			expTrunc: true,
+		},
+		{
+			input:    "123abc",
+			exp:      "123",
+			expTrunc: true,
+		},
+		{
+			input:    "abc",
+			exp:      "0",
+			expTrunc: true,
+		},
+		{
+			// Leading sign is fine
+			input:    "+123",
+			exp:      "+123",
+			expTrunc: false,
+		},
+		{
+			// Leading sign is fine
+			input:    "-123",
+			exp:      "-123",
+			expTrunc: false,
+		},
+		{
+			// Repeated signs
+			input:    "+-+-+-123",
+			exp:      "0",
+			expTrunc: true,
+		},
+		{
+			// Space after sign
+			input:    "+ 123",
+			exp:      "0",
+			expTrunc: true,
+		},
+		{
+			// Valid float strings are not valid ints
+			input:    "1.23",
+			exp:      "1",
+			expTrunc: true,
+		},
+		{
+			// Scientific float notation is not valid
+			input:    "123.456e10",
+			exp:      "123",
+			expTrunc: true,
+		},
+		{
+			// Scientific notation is not valid
+			input:    "123e10",
+			exp:      "123",
+			expTrunc: true,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(fmt.Sprintf("%v", test.input), func(t *testing.T) {
+			truncStr, didTrunc := TruncateStringToInt(test.input)
+			assert.Equal(t, test.exp, truncStr)
+			assert.Equal(t, test.expTrunc, didTrunc)
+		})
+	}
+}
+
+func TestTruncateStringToDouble(t *testing.T) {
+	tests := []struct {
+		input    string
+		exp      string
+		expTrunc bool
+	}{
+		{
+			input:    "1",
+			exp:      "1",
+			expTrunc: false,
+		},
+		{
+			// Whitespace does not count as truncation
+			input:    " \t\n 1 \t\n ",
+			exp:      "1",
+			expTrunc: false,
+		},
+		{
+			input:    "123abc",
+			exp:      "123",
+			expTrunc: true,
+		},
+		{
+			input:    "abc",
+			exp:      "0",
+			expTrunc: true,
+		},
+		{
+			// Leading sign is fine
+			input:    "+123",
+			exp:      "+123",
+			expTrunc: false,
+		},
+		{
+			// Leading sign is fine
+			input:    "-123",
+			exp:      "-123",
+			expTrunc: false,
+		},
+		{
+			// Repeated signs
+			input:    "+-+-+-123",
+			exp:      "0",
+			expTrunc: true,
+		},
+		{
+			// Space after sign
+			input:    "+ 123",
+			exp:      "0",
+			expTrunc: true,
+		},
+		{
+			// Valid float strings are not valid ints
+			input:    "1.23",
+			exp:      "1.23",
+			expTrunc: false,
+		},
+		{
+			// Scientific notation
+			input:    "123.456e10",
+			exp:      "123.456e10",
+			expTrunc: false,
+		},
+		{
+			// Scientific notation
+			input:    "123e10",
+			exp:      "123e10",
+			expTrunc: false,
+		},
+		{
+			// Scientific notation
+			input:    "+123.456e-10",
+			exp:      "+123.456e-10",
+			expTrunc: false,
+		},
+		{
+			// Scientific notation truncates
+			input:    "+123.456e-10notaumber",
+			exp:      "+123.456e-10",
+			expTrunc: true,
+		},
+		{
+			// Invalid Scientific notation
+			input:    "e123",
+			exp:      "0",
+			expTrunc: true,
+		},
+		{
+			// Invalid Scientific notation
+			input:    ".e1",
+			exp:      "0",
+			expTrunc: true,
+		},
+		{
+			// Invalid Scientific notation
+			input:    "1e2e3",
+			exp:      "1e2",
+			expTrunc: true,
+		},
+		{
+			input:    ".0e123",
+			exp:      ".0e123",
+			expTrunc: false,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(fmt.Sprintf("%v", test.input), func(t *testing.T) {
+			truncStr, didTrunc := TruncateStringToDouble(test.input)
+			assert.Equal(t, test.exp, truncStr)
+			assert.Equal(t, test.expTrunc, didTrunc)
+		})
+	}
+}