diff --git a/test/functions_logic_test.dart b/test/functions_logic_test.dart
new file mode 100644
index 0000000..c567610
--- /dev/null
+++ b/test/functions_logic_test.dart
@@ -0,0 +1,79 @@
+import 'package:cellar/cellar.dart';
+import 'package:test/test.dart';
+
+CellValue ev(String formula) {
+  final sheet = Sheet();
+  sheet.setValue('Z1', formula);
+  return sheet.valueOf('Z1');
+}
+
+double num(CellValue value) => (value as NumberValue).value;
+
+void main() {
+  group('logical functions', () {
+    test('IF chooses a branch', () {
+      expect(ev('=IF(2>1, "yes", "no")'), const TextValue('yes'));
+      expect(ev('=IF(2<1, "yes", "no")'), const TextValue('no'));
+    });
+
+    test('IFS picks the first true condition', () {
+      expect(ev('=IFS(FALSE, 1, TRUE, 2, TRUE, 3)'), const NumberValue(2));
+      expect(ev('=IFS(FALSE, 1, FALSE, 2)'), const ErrorValue(ErrorKind.na));
+    });
+
+    test('SWITCH matches a value with a default', () {
+      expect(ev('=SWITCH(2, 1, "a", 2, "b", "z")'), const TextValue('b'));
+      expect(ev('=SWITCH(9, 1, "a", 2, "b", "z")'), const TextValue('z'));
+      expect(ev('=SWITCH(9, 1, "a")'), const ErrorValue(ErrorKind.na));
+    });
+
+    test('AND OR NOT XOR', () {
+      expect(ev('=AND(TRUE, 1=1, 2>1)'), const BooleanValue(true));
+      expect(ev('=OR(FALSE, 1=2, 3>1)'), const BooleanValue(true));
+      expect(ev('=NOT(1=1)'), const BooleanValue(false));
+      expect(ev('=XOR(TRUE, TRUE, TRUE)'), const BooleanValue(true));
+      expect(ev('=XOR(TRUE, TRUE)'), const BooleanValue(false));
+    });
+
+    test('IFERROR and IFNA', () {
+      expect(num(ev('=IFERROR(1/0, 42)')), 42);
+      expect(num(ev('=IFERROR(5, 42)')), 5);
+      expect(num(ev('=IFNA(NA(), 7)')), 7);
+      expect(ev('=IFNA(1/0, 7)'), const ErrorValue(ErrorKind.divZero));
+    });
+  });
+
+  group('info functions', () {
+    test('type predicates', () {
+      expect(ev('=ISNUMBER(5)'), const BooleanValue(true));
+      expect(ev('=ISTEXT("x")'), const BooleanValue(true));
+      expect(ev('=ISLOGICAL(TRUE)'), const BooleanValue(true));
+      expect(ev('=ISNUMBER("x")'), const BooleanValue(false));
+    });
+
+    test('error predicates', () {
+      expect(ev('=ISERROR(1/0)'), const BooleanValue(true));
+      expect(ev('=ISERR(1/0)'), const BooleanValue(true));
+      expect(ev('=ISERR(NA())'), const BooleanValue(false));
+      expect(ev('=ISNA(NA())'), const BooleanValue(true));
+      expect(ev('=ISNA(1/0)'), const BooleanValue(false));
+    });
+
+    test('ISBLANK reflects an empty cell', () {
+      final sheet = Sheet();
+      sheet.setValue('B1', '=ISBLANK(A1)');
+      sheet.setValue('B2', '=ISBLANK(A2)');
+      sheet.setValue('A2', 'x');
+      expect(sheet.valueOf('B1'), const BooleanValue(true));
+      expect(sheet.valueOf('B2'), const BooleanValue(false));
+    });
+
+    test('N and TYPE', () {
+      expect(num(ev('=N(TRUE)')), 1);
+      expect(num(ev('=N("text")')), 0);
+      expect(num(ev('=TYPE(5)')), 1);
+      expect(num(ev('=TYPE("x")')), 2);
+      expect(num(ev('=TYPE(1/0)')), 16);
+    });
+  });
+}
diff --git a/test/functions_lookup_test.dart b/test/functions_lookup_test.dart
new file mode 100644
index 0000000..404fcf6
--- /dev/null
+++ b/test/functions_lookup_test.dart
@@ -0,0 +1,93 @@
+import 'package:cellar/cellar.dart';
+import 'package:test/test.dart';
+
+double num(CellValue value) => (value as NumberValue).value;
+
+Sheet lookupSheet() {
+  final sheet = Sheet();
+  final rows = [
+    ['apple', '1', 'red'],
+    ['banana', '2', 'yellow'],
+    ['cherry', '3', 'red'],
+  ];
+  for (var r = 0; r < rows.length; r++) {
+    sheet.setValue('A${r + 1}', rows[r][0]);
+    sheet.setValue('B${r + 1}', rows[r][1]);
+    sheet.setValue('C${r + 1}', rows[r][2]);
+  }
+  return sheet;
+}
+
+void main() {
+  group('lookup functions', () {
+    test('VLOOKUP exact match returns another column', () {
+      final sheet = lookupSheet();
+      sheet.setValue('E1', '=VLOOKUP("banana", A1:C3, 3, FALSE)');
+      expect(sheet.valueOf('E1'), const TextValue('yellow'));
+    });
+
+    test('VLOOKUP approximate on sorted numbers', () {
+      final sheet = Sheet();
+      sheet.setValue('A1', '0');
+      sheet.setValue('B1', 'low');
+      sheet.setValue('A2', '10');
+      sheet.setValue('B2', 'mid');
+      sheet.setValue('A3', '20');
+      sheet.setValue('B3', 'high');
+      sheet.setValue('D1', '=VLOOKUP(15, A1:B3, 2)');
+      expect(sheet.valueOf('D1'), const TextValue('mid'));
+    });
+
+    test('VLOOKUP missing exact key is #N/A', () {
+      final sheet = lookupSheet();
+      sheet.setValue('E1', '=VLOOKUP("mango", A1:C3, 2, FALSE)');
+      expect(sheet.valueOf('E1'), const ErrorValue(ErrorKind.na));
+    });
+
+    test('HLOOKUP across a row', () {
+      final sheet = Sheet();
+      sheet.setValue('A1', 'Q1');
+      sheet.setValue('B1', 'Q2');
+      sheet.setValue('C1', 'Q3');
+      sheet.setValue('A2', '10');
+      sheet.setValue('B2', '20');
+      sheet.setValue('C2', '30');
+      sheet.setValue('E1', '=HLOOKUP("Q2", A1:C2, 2, FALSE)');
+      expect(num(sheet.valueOf('E1')), 20);
+    });
+
+    test('MATCH exact and approximate', () {
+      final sheet = lookupSheet();
+      sheet.setValue('E1', '=MATCH("cherry", A1:A3, 0)');
+      expect(num(sheet.valueOf('E1')), 3);
+      final numbers = Sheet();
+      numbers.setValue('A1', '10');
+      numbers.setValue('A2', '20');
+      numbers.setValue('A3', '30');
+      numbers.setValue('B1', '=MATCH(25, A1:A3, 1)');
+      expect(num(numbers.valueOf('B1')), 2);
+    });
+
+    test('INDEX and INDEX/MATCH', () {
+      final sheet = lookupSheet();
+      sheet.setValue('E1', '=INDEX(A1:C3, 2, 3)');
+      sheet.setValue('E2', '=INDEX(B1:B3, MATCH("cherry", A1:A3, 0))');
+      expect(sheet.valueOf('E1'), const TextValue('yellow'));
+      expect(num(sheet.valueOf('E2')), 3);
+    });
+
+    test('CHOOSE ROWS COLUMNS ROW COLUMN', () {
+      final sheet = lookupSheet();
+      sheet.setValue('E1', '=CHOOSE(2, "a", "b", "c")');
+      sheet.setValue('E2', '=ROWS(A1:C3)');
+      sheet.setValue('E3', '=COLUMNS(A1:C3)');
+      sheet.setValue('E4', '=ROW(B5)');
+      sheet.setValue('E5', '=COLUMN(D2)');
+      expect(sheet.valueOf('E1'), const TextValue('b'));
+      expect(num(sheet.valueOf('E2')), 3);
+      expect(num(sheet.valueOf('E3')), 3);
+      expect(num(sheet.valueOf('E4')), 5);
+      expect(num(sheet.valueOf('E5')), 4);
+    });
+  });
+}
diff --git a/test/functions_text_test.dart b/test/functions_text_test.dart
new file mode 100644
index 0000000..d169635
--- /dev/null
+++ b/test/functions_text_test.dart
@@ -0,0 +1,72 @@
+import 'package:cellar/cellar.dart';
+import 'package:test/test.dart';
+
+CellValue ev(String formula) {
+  final sheet = Sheet();
+  sheet.setValue('Z1', formula);
+  return sheet.valueOf('Z1');
+}
+
+double num(CellValue value) => (value as NumberValue).value;
+
+void main() {
+  group('text functions', () {
+    test('slicing', () {
+      expect(ev('=LEFT("spreadsheet", 6)'), const TextValue('spread'));
+      expect(ev('=RIGHT("spreadsheet", 5)'), const TextValue('sheet'));
+      expect(ev('=MID("spreadsheet", 7, 5)'), const TextValue('sheet'));
+      expect(num(ev('=LEN("hello")')), 5);
+    });
+
+    test('case and proper', () {
+      expect(ev('=UPPER("cellar")'), const TextValue('CELLAR'));
+      expect(ev('=LOWER("CELLAR")'), const TextValue('cellar'));
+      expect(ev('=PROPER("john the FIRST")'), const TextValue('John The First'));
+      expect(ev('=TRIM("  a   b  ")'), const TextValue('a b'));
+    });
+
+    test('concat and textjoin', () {
+      expect(ev('=CONCAT("foo", "bar")'), const TextValue('foobar'));
+      expect(ev('=TEXTJOIN("-", TRUE, "a", "", "b")'), const TextValue('a-b'));
+      expect(ev('=TEXTJOIN("-", FALSE, "a", "", "b")'), const TextValue('a--b'));
+    });
+
+    test('substitute and replace', () {
+      expect(ev('=SUBSTITUTE("a-b-c", "-", "+")'), const TextValue('a+b+c'));
+      expect(ev('=SUBSTITUTE("a-b-c", "-", "+", 2)'), const TextValue('a-b+c'));
+      expect(ev('=REPLACE("abcdef", 2, 3, "XY")'), const TextValue('aXYef'));
+    });
+
+    test('find and search', () {
+      expect(num(ev('=FIND("c", "abcabc")')), 3);
+      expect(num(ev('=SEARCH("C", "abcabc")')), 3);
+      expect(ev('=FIND("z", "abc")'), const ErrorValue(ErrorKind.value));
+    });
+
+    test('char and code', () {
+      expect(ev('=CHAR(65)'), const TextValue('A'));
+      expect(num(ev('=CODE("A")')), 65);
+    });
+
+    test('value and numbervalue', () {
+      expect(num(ev('=VALUE("42.5")')), 42.5);
+      expect(num(ev('=NUMBERVALUE("1.234,50", ",", ".")')), 1234.5);
+    });
+
+    test('TEXT formats a number', () {
+      expect(ev('=TEXT(1234.5, "#,##0.00")'), const TextValue('1,234.50'));
+      expect(ev('=TEXT(0.25, "0.0%")'), const TextValue('25.0%'));
+    });
+
+    test('regex helpers', () {
+      expect(ev('=REGEXMATCH("abc123", "[0-9]+")'), const BooleanValue(true));
+      expect(ev('=REGEXEXTRACT("order 42 done", "([0-9]+)")'), const TextValue('42'));
+      expect(ev('=REGEXREPLACE("a1b2c3", "[0-9]", "#")'), const TextValue('a#b#c#'));
+    });
+
+    test('REPT and EXACT', () {
+      expect(ev('=REPT("ab", 3)'), const TextValue('ababab'));
+      expect(ev('=EXACT("Abc", "abc")'), const BooleanValue(false));
+    });
+  });
+}