diff --git a/src/schema/field/arrays/allowed.ts b/src/schema/field/arrays/allowed.ts
index df706e2..edd450e 100644
--- a/src/schema/field/arrays/allowed.ts
+++ b/src/schema/field/arrays/allowed.ts
@@ -26,8 +26,7 @@
 import {type SchemaFieldType} from '../type';
 
 /**
- * Determine if array support is enabled based on all supported types for a single
- * schema field.
+ * Determine if field supports array values based on field types.
  * @param items		Field types to check.
  *
  * @category		Schema – Field
diff --git a/src/transform/verified.ts b/src/transform/verified.ts
index ebeae6e..2e5fb00 100644
--- a/src/transform/verified.ts
+++ b/src/transform/verified.ts
@@ -27,7 +27,7 @@ import {Fate} from '@toreda/fate';
 import {Log} from '@toreda/log';
 import {schemaError} from '../schema/error';
 import {type VerifiedMap} from '../verified/map';
-import {Transformed} from '../transformed';
+import {type Transformed} from '../transformed';
 import {transformVerifiedField} from './verified/field';
 
 /**
diff --git a/src/transformed/field.ts b/src/transformed/field.ts
index 8d0fa8e..c235d26 100644
--- a/src/transformed/field.ts
+++ b/src/transformed/field.ts
@@ -24,6 +24,8 @@
  */
 
 /**
+ * Type returned by functions that transform verified field data. Fields may contain
+ * scalar values, nulls, subfields, and arrays containing the former.
  * @param			id
  * @param			data
  * @param			base
diff --git a/tests/empty.spec.ts b/tests/empty.spec.ts
new file mode 100644
index 0000000..413fe5a
--- /dev/null
+++ b/tests/empty.spec.ts
@@ -0,0 +1,67 @@
+import {empty} from '../src/empty';
+const EMPTY_ARRAY: string[] = [];
+
+describe('empty', () => {
+	it(`should return false when value is undefined`, () => {
+		expect(empty<any>(undefined)).toBe(false);
+	});
+
+	it(`should return false when value is null`, () => {
+		expect(empty<any>(null)).toBe(false);
+	});
+
+	it(`should return false when value is a non-empty array`, () => {
+		expect(empty<any>([11, 'aa'])).toBe(false);
+	});
+
+	it(`should return true when value is an empty array`, () => {
+		expect(empty<any>(EMPTY_ARRAY)).toBe(true);
+	});
+
+	it(`should return true when value is an empty object`, () => {
+		expect(empty<any>({})).toBe(true);
+	});
+
+	it(`should return false when value is a non-empty string`, () => {
+		expect(empty<any>('aaaaaa')).toBe(false);
+	});
+
+	it(`should return false when value is a non-empty string`, () => {
+		expect(empty<any>('aaaaaa')).toBe(false);
+	});
+
+	it(`should return true when value is a space-padded empty string`, () => {
+		let value = ' ';
+
+		for (let i = 0; i < 5; i++) {
+			expect(empty<any>(value)).toBe(true);
+			value += ' ';
+		}
+	});
+
+	it(`should return true when value is an non-empty object`, () => {
+		expect(
+			empty<any>({
+				one: 'aaaaa'
+			})
+		).toBe(false);
+	});
+
+	it(`should return false when value is a boolean (true)`, () => {
+		expect(empty<boolean>(true)).toBe(false);
+	});
+
+	it(`should return false when value is a boolean (true)`, () => {
+		expect(empty<boolean>(false)).toBe(false);
+	});
+
+	it(`should return false when value is a falsy number (0)`, () => {
+		expect(empty<number>(0)).toBe(false);
+	});
+
+	it(`should return false when value is a truthy number`, () => {
+		expect(empty<number>(1)).toBe(false);
+		expect(empty<number>(10000)).toBe(false);
+		expect(empty<number>(-1)).toBe(false);
+	});
+});
diff --git a/tests/schema/field/arrays/allowed.spec.ts b/tests/schema/field/arrays/allowed.spec.ts
new file mode 100644
index 0000000..502bce5
--- /dev/null
+++ b/tests/schema/field/arrays/allowed.spec.ts
@@ -0,0 +1,123 @@
+import {SchemaFieldType} from '../../../../src';
+import {schemaFieldArraysAllowed} from '../../../../src/schema/field/arrays/allowed';
+import {schemaFieldTypes} from '../../../../src/schema/field/types';
+
+const EMPTY_STRING = '';
+const EMPTY_OBJECT = {};
+const EMPTY_STR_ARRAY: string[] = [];
+
+const NON_ARRAY_TYPES: SchemaFieldType[] = [
+	'bigint',
+	'BigInt',
+	'boolean',
+	'datetime',
+	'dbl',
+	'double',
+	'float',
+	'int',
+	'iterable',
+	'json',
+	'null',
+	'number',
+	'serialized',
+	'string',
+	'time',
+	'uint',
+	'undefined',
+	'url'
+];
+
+const ARRAY_TYPES: SchemaFieldType<string>[] = [
+	'bigint[]',
+	'BigInt[]',
+	'boolean[]',
+	'datetime[]',
+	'datetime[]',
+	'dbl[]',
+	'double[]',
+	'float[]',
+	'int[]',
+	'iterable[]',
+	'json[]',
+	'null[]',
+	'number[]',
+	'serialized[]',
+	'string[]',
+	'time[]',
+	'undefined[]',
+	'url[]'
+];
+
+describe('schemaFieldArraysAllowed', () => {
+	it(`should return false when items arg is an empty string`, () => {
+		expect(schemaFieldArraysAllowed<string>(EMPTY_STRING as any)).toBe(false);
+	});
+
+	it(`should return false when items arg is a string`, () => {
+		expect(schemaFieldArraysAllowed<string>('f087145081-998132' as any)).toBe(false);
+	});
+
+	it(`should return false when items arg is an empty array`, () => {
+		expect(schemaFieldArraysAllowed<string>(EMPTY_STR_ARRAY as any)).toBe(false);
+	});
+
+	it(`should return false when items arg is an empty object`, () => {
+		expect(schemaFieldArraysAllowed<string>(EMPTY_OBJECT as any)).toBe(false);
+	});
+
+	it(`should return false for all built-in non-array types'`, () => {
+		expect(schemaFieldArraysAllowed<string>(NON_ARRAY_TYPES)).toBe(false);
+	});
+
+	it(`should return true when one item is an array type among non-array types`, () => {
+		const input: SchemaFieldType<string>[] = [...NON_ARRAY_TYPES, 'number[]'];
+		expect(schemaFieldArraysAllowed<string>(input)).toBe(true);
+	});
+
+	it(`should return true when items array has one array type`, () => {
+		expect(schemaFieldArraysAllowed<string>(['BigInt[]'])).toBe(true);
+	});
+
+	for (const fieldType of NON_ARRAY_TYPES) {
+		it(`should return false when items arg is a single non-array type '${fieldType}'`, () => {
+			expect(schemaFieldArraysAllowed<string>([fieldType])).toBe(false);
+		});
+	}
+
+	for (const fieldType of ARRAY_TYPES) {
+		it(`should return true when items array has one array type '${fieldType}'`, () => {
+			expect(schemaFieldArraysAllowed<string>([fieldType])).toBe(true);
+		});
+	}
+
+	it(`should return true when the last item is an array type and all other elements are skipped due to being non-strings`, () => {
+		expect(
+			schemaFieldArraysAllowed<string>([
+				undefined,
+				null,
+				1000,
+				{},
+				[],
+				'___',
+				EMPTY_STRING,
+				'BigInt[]'
+			] as any)
+		).toBe(true);
+	});
+
+	it(`should return true when items arg contains a non-builtin type ending in '[]'`, () => {
+		expect(
+			schemaFieldArraysAllowed<string>([
+				null,
+				undefined,
+				10,
+				100,
+				91910,
+				'---',
+				'string',
+				'undefined',
+				'customtype[]'
+			] as any)
+		).toBe(true);
+	});
+});
diff --git a/tests/transform/verified.spec.ts b/tests/transform/verified.spec.ts
new file mode 100644
index 0000000..efd632d
--- /dev/null
+++ b/tests/transform/verified.spec.ts
@@ -0,0 +1,46 @@
+import {Primitive} from '@toreda/types';
+import {transformVerified} from '../../src/transform/verified';
+import {schemaError} from '../../src';
+import {Levels, Log} from '@toreda/log';
+
+describe('transformVerified', () => {
+	let verifiedMap: Map<string, string>;
+	let base: Log;
+
+	beforeAll(() => {
+		verifiedMap = new Map<string, string>();
+		base = new Log({
+			consoleEnabled: true,
+			globalLevel: Levels.ALL,
+			groupsStartEnabled: true
+		});
+	});
+
+	beforeEach(() => {
+		verifiedMap.clear();
+	});
+
+	describe('Base parameters', () => {
+		it(`should fail with code when base arg is undefined`, async () => {
+			const result = await transformVerified<Primitive, any>(verifiedMap, undefined as any);
+			expect(result.ok()).toBe(false);
+
+			expect(result.errorCode()).toBe(schemaError('missing_argument', 'transformVerified', 'base'));
+		});
+
+		it(`should fail with code when base arg is null`, async () => {
+			const result = await transformVerified<Primitive, any>(verifiedMap, null as any);
+			expect(result.ok()).toBe(false);
+
+			expect(result.errorCode()).toBe(schemaError('missing_argument', 'transformVerified', 'base'));
+		});
+
+		it(`should succeed when input is an empty map`, async () => {
+			expect(verifiedMap.size).toBe(0);
+
+			const result = await transformVerified<Primitive, any>(verifiedMap, base);
+			expect(result.ok()).toBe(true);
+			expect(result.data).toStrictEqual({});
+		});
+	});
+});