diff --git a/app/Support/Nutrients.php b/app/Support/Nutrients.php
index 346e39d..4ea4e89 100644
--- a/app/Support/Nutrients.php
+++ b/app/Support/Nutrients.php
@@ -71,12 +71,6 @@ class Nutrients
 
     /**
      * Calculate a nutrient multiplier for a Food.
-     *
-     * @param \App\Models\Food $food
-     * @param float $amount
-     * @param string|null $fromUnit
-     *
-     * @return float
      */
     public static function calculateFoodNutrientMultiplier(
         Food $food,
@@ -93,6 +87,7 @@ class Nutrients
             return $amount / $food->serving_weight;
         }
 
+        // @todo Determine if `empty($food->serving_unit)` case makes sense.
         if (
             empty($fromUnit)
             || empty($food->serving_unit)
@@ -130,13 +125,6 @@ class Nutrients
 
     /**
      * Calculate a nutrient amount for a recipe.
-     *
-     * @param \App\Models\Recipe $recipe
-     * @param string $nutrient
-     * @param float $amount
-     * @param string $fromUnit
-     *
-     * @return float
      */
     public static function calculateRecipeNutrientAmount(
         Recipe $recipe,
diff --git a/database/factories/FoodFactory.php b/database/factories/FoodFactory.php
index 4cbd4cf..5e45f68 100644
--- a/database/factories/FoodFactory.php
+++ b/database/factories/FoodFactory.php
@@ -8,21 +8,81 @@ use Illuminate\Database\Eloquent\Factories\Factory;
 class FoodFactory extends Factory
 {
     /**
-     * The name of the factory's corresponding model.
-     *
-     * @var string
+     * {@inheritdoc}
      */
     protected $model = Food::class;
 
     /**
-     * Define the model's default state.
-     *
-     * @return array
+     * {@inheritdoc}
      */
-    public function definition()
+    public function definition(): array
     {
         return [
-            //
+            'name' => $this->faker->word,
+            'detail' => $this->faker->sentence(2),
+            'brand' => $this->faker->word,
+            'source' => $this->faker->url,
+            'serving_size' => $this->faker->randomFloat(2, 1/2, 5),
+            'serving_unit' => $this->faker->randomElement(['tsp', 'tbsp', 'cup']),
+            'serving_weight' => $this->faker->numberBetween(5, 500),
+            'calories' => $this->faker->randomFloat(2, 0, 100),
+            'fat' => $this->faker->randomFloat(2, 0, 10),
+            'cholesterol' => $this->faker->randomFloat(2, 0, 100),
+            'sodium' => $this->faker->randomFloat(2, 0, 500),
+            'carbohydrates' => $this->faker->randomFloat(2, 0, 20),
+            'protein' => $this->faker->randomFloat(2, 0, 20),
         ];
     }
+
+    /**
+     * Make instance with "tsp" serving unit.
+     */
+    public function tspServingUnit()
+    {
+        return $this->state(function (array $attributes) {
+            return [
+                'serving_unit' => 'tsp',
+                'serving_size' => 1,
+            ];
+        });
+    }
+
+    /**
+     * Make instance with "tbsp" serving unit.
+     */
+    public function tbspServingUnit()
+    {
+        return $this->state(function (array $attributes) {
+            return [
+                'serving_unit' => 'tbsp',
+                'serving_size' => 1,
+            ];
+        });
+    }
+
+    /**
+     * Make instance with "cup" serving unit.
+     */
+    public function cupServingUnit()
+    {
+        return $this->state(function (array $attributes) {
+            return [
+                'serving_unit' => 'cup',
+                'serving_size' => 1,
+            ];
+        });
+    }
+
+    /**
+     * Make instance with no" serving unit.
+     */
+    public function noServingUnit()
+    {
+        return $this->state(function (array $attributes) {
+            return [
+                'serving_unit' => null,
+                'serving_unit_name' => 'head'
+            ];
+        });
+    }
 }
diff --git a/phpunit.xml b/phpunit.xml
index 4ae4d97..76a606b 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -21,8 +21,8 @@
         <server name="APP_ENV" value="testing"/>
         <server name="BCRYPT_ROUNDS" value="4"/>
         <server name="CACHE_DRIVER" value="array"/>
-        <!-- <server name="DB_CONNECTION" value="sqlite"/> -->
-        <!-- <server name="DB_DATABASE" value=":memory:"/> -->
+        <server name="DB_CONNECTION" value="sqlite"/>
+        <server name="DB_DATABASE" value=":memory:"/>
         <server name="MAIL_MAILER" value="array"/>
         <server name="QUEUE_CONNECTION" value="sync"/>
         <server name="SESSION_DRIVER" value="array"/>
diff --git a/tests/Feature/ExampleTest.php b/tests/Feature/ExampleTest.php
deleted file mode 100644
index cdb5111..0000000
--- a/tests/Feature/ExampleTest.php
+++ /dev/null
@@ -1,21 +0,0 @@
-<?php
-
-namespace Tests\Feature;
-
-use Illuminate\Foundation\Testing\RefreshDatabase;
-use Tests\TestCase;
-
-class ExampleTest extends TestCase
-{
-    /**
-     * A basic test example.
-     *
-     * @return void
-     */
-    public function testBasicTest()
-    {
-        $response = $this->get('/');
-
-        $response->assertStatus(200);
-    }
-}
diff --git a/tests/Feature/RegistrationTest.php b/tests/Feature/RegistrationTest.php
deleted file mode 100644
index 6dd5ff8..0000000
--- a/tests/Feature/RegistrationTest.php
+++ /dev/null
@@ -1,32 +0,0 @@
-<?php
-
-namespace Tests\Feature;
-
-use App\Providers\RouteServiceProvider;
-use Illuminate\Foundation\Testing\RefreshDatabase;
-use Tests\TestCase;
-
-class RegistrationTest extends TestCase
-{
-    use RefreshDatabase;
-
-    public function test_registration_screen_can_be_rendered()
-    {
-        $response = $this->get('/register');
-
-        $response->assertStatus(200);
-    }
-
-    public function test_new_users_can_register()
-    {
-        $response = $this->post('/register', [
-            'name' => 'Test User',
-            'email' => 'test@example.com',
-            'password' => 'password',
-            'password_confirmation' => 'password',
-        ]);
-
-        $this->assertAuthenticated();
-        $response->assertRedirect(RouteServiceProvider::HOME);
-    }
-}
diff --git a/tests/Feature/Support/NutrientsTest.php b/tests/Feature/Support/NutrientsTest.php
new file mode 100644
index 0000000..81cc776
--- /dev/null
+++ b/tests/Feature/Support/NutrientsTest.php
@@ -0,0 +1,104 @@
+<?php
+
+namespace Tests\Feature\Support;
+
+use App\Models\Food;
+use App\Support\Nutrients;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+class NutrientsTest extends TestCase
+{
+    use RefreshDatabase;
+
+    /**
+     * Test invalid Food nutrient multiplier calculation.
+     *
+     * @dataProvider foodsInvalidNutrientMultipliersProvider
+     */
+    public function testCalculateFoodInvalidNutrientMultiplier(
+        Food $food,
+        float $amount,
+        string $fromUnit,
+    ): void {
+        $this->expectException(\DomainException::class);
+        Nutrients::calculateFoodNutrientMultiplier($food, $amount, $fromUnit);
+    }
+
+    /**
+     * Test valid Food nutrient multiplier calculation.
+     *
+     * @dataProvider foodsValidNutrientMultipliersProvider
+     */
+    public function testCalculateFoodValidNutrientMultiplier(
+        Food $food,
+        float $amount,
+        string $fromUnit,
+        float $expectedMultiplier
+    ): void {
+        $this->assertEquals(
+            Nutrients::calculateFoodNutrientMultiplier($food, $amount, $fromUnit),
+            $expectedMultiplier
+        );
+    }
+
+    /**
+     * Data providers.
+     */
+
+    /**
+     * Provide example foods and expected nutrient multipliers.
+     */
+    public function foodsInvalidNutrientMultipliersProvider(): array {
+        $this->refreshApplication();
+
+        /** @var \App\Models\Food $foodInvalidUnit */
+        $foodInvalidUnit = Food::factory()->make(['serving_unit' => 'invalid']);
+
+        return [
+            [$foodInvalidUnit, 1, 'tsp'],
+            [$foodInvalidUnit, 1, 'tbsp'],
+            [$foodInvalidUnit, 1, 'cup'],
+            [Food::factory()->tspServingUnit()->make(), 1, 'invalid'],
+        ];
+    }
+
+    /**
+     * Provide example foods and expected nutrient multipliers.
+     */
+    public function foodsValidNutrientMultipliersProvider(): array {
+        $this->refreshApplication();
+
+        /** @var \App\Models\Food[] $foods */
+        $foods = [
+            'tsp' => Food::factory()->tspServingUnit()->make(),
+            'tbsp' => Food::factory()->tbspServingUnit()->make(),
+            'cup' => Food::factory()->cupServingUnit()->make(),
+            'none' => Food::factory()->noServingUnit()->make(),
+        ];
+
+        return [
+            [$foods['tsp'], $foods['tsp']->serving_weight, 'oz', Nutrients::$gramsPerOunce],
+            [$foods['tsp'], 1, 'serving', 1],
+            [$foods['tsp'], $foods['tsp']->serving_weight * 1.5, 'gram', 1.5],
+            [$foods['tsp'], 2, 'tsp', 2],
+            [$foods['tsp'], 1, 'tbsp', 3],
+            [$foods['tsp'], 1, 'cup', 48],
+            [$foods['tbsp'], $foods['tbsp']->serving_weight, 'oz', Nutrients::$gramsPerOunce],
+            [$foods['tbsp'], 1, 'serving', 1],
+            [$foods['tbsp'], $foods['tbsp']->serving_weight * 2, 'gram', 2],
+            [$foods['tbsp'], 2, 'tsp', 2/3],
+            [$foods['tbsp'], 1, 'tbsp', 1],
+            [$foods['tbsp'], 2, 'cup', 32],
+            [$foods['cup'], $foods['cup']->serving_weight, 'oz', Nutrients::$gramsPerOunce],
+            [$foods['cup'], 1, 'serving', 1],
+            [$foods['cup'], $foods['cup']->serving_weight * 2.25, 'gram', 2.25],
+            [$foods['cup'], 3, 'tsp', 1/16],
+            [$foods['cup'], 2, 'tbsp', 1/8],
+            [$foods['cup'], 5, 'cup', 5],
+            [$foods['none'], $foods['none']->serving_weight, 'oz', Nutrients::$gramsPerOunce],
+            [$foods['none'], 1, 'serving', 1],
+            [$foods['none'], $foods['none']->serving_weight * 3.0125, 'gram', 3.0125],
+        ];
+    }
+}
diff --git a/tests/Unit/ExampleTest.php b/tests/Unit/ExampleTest.php
deleted file mode 100644
index 358cfc8..0000000
--- a/tests/Unit/ExampleTest.php
+++ /dev/null
@@ -1,18 +0,0 @@
-<?php
-
-namespace Tests\Unit;
-
-use PHPUnit\Framework\TestCase;
-
-class ExampleTest extends TestCase
-{
-    /**
-     * A basic test example.
-     *
-     * @return void
-     */
-    public function testBasicTest()
-    {
-        $this->assertTrue(true);
-    }
-}
diff --git a/tests/Unit/Support/ArrayFormatTest.php b/tests/Unit/Support/ArrayFormatTest.php
new file mode 100644
index 0000000..8753126
--- /dev/null
+++ b/tests/Unit/Support/ArrayFormatTest.php
@@ -0,0 +1,40 @@
+<?php
+
+namespace Tests\Unit\Support;
+
+use App\Support\ArrayFormat;
+use PHPUnit\Framework\TestCase;
+
+class ArrayFormatTest extends TestCase
+{
+
+    /**
+     * Test input array "flipping".
+     *
+     * @see \App\Support\ArrayFormat::flipTwoDimensionalKeys()
+     */
+    public function testFlipTwoDimensionalKeys(): void
+    {
+        $input = [
+            'ingredient' => [
+                0 => 'ingredient-0',
+                1 => 'ingredient-1',
+                2 => 'ingredient-2',
+                3 => 'ingredient-3',
+            ],
+            'amount' => [
+                0 => 'amount-0',
+                1 => 'amount-1',
+                2 => 'amount-2',
+                3 => 'amount-3',
+            ],
+        ];
+        $expected = [
+            ['ingredient' => 'ingredient-0', 'amount' => 'amount-0'],
+            ['ingredient' => 'ingredient-1', 'amount' => 'amount-1'],
+            ['ingredient' => 'ingredient-2', 'amount' => 'amount-2'],
+            ['ingredient' => 'ingredient-3', 'amount' => 'amount-3'],
+        ];
+        $this->assertEqualsCanonicalizing($expected, ArrayFormat::flipTwoDimensionalKeys($input));
+    }
+}
diff --git a/tests/Unit/Support/NumberTest.php b/tests/Unit/Support/NumberTest.php
new file mode 100644
index 0000000..df39737
--- /dev/null
+++ b/tests/Unit/Support/NumberTest.php
@@ -0,0 +1,70 @@
+<?php
+
+namespace Tests\Unit\Support;
+
+use App\Support\Number;
+use PHPUnit\Framework\TestCase;
+
+class NumberTest extends TestCase
+{
+
+    /**
+     * Test float to string conversion.
+     *
+     * @dataProvider decimalStringFloatsProvider
+     * @dataProvider fractionStringFloatsProvider
+     *
+     * @see \App\Support\Number::floatFromString()
+     */
+    public function testFloatFromString(string $string, float $expectedFloat): void
+    {
+        $result = Number::floatFromString($string);
+        $this->assertIsFloat($result);
+        $this->assertEquals($expectedFloat, $result);
+    }
+
+    /**
+     * Test (fraction) string to float conversion.
+     *
+     * @dataProvider fractionStringFloatsProvider
+     *
+     * @see \App\Support\Number::fractionStringFromFloat()
+     */
+    public function testFractionStringFromFloat(string $expectedString, float $float): void
+    {
+        $result = Number::fractionStringFromFloat($float);
+        $this->assertIsString($result);
+        $this->assertEquals($expectedString, $result);
+    }
+
+    /**
+     * Data providers.
+     */
+
+    /**
+     * Provide decimal string and float data.
+     *
+     * @see \Tests\Unit\Support\NumberTest::testFloatFromString()
+     */
+    public function decimalStringFloatsProvider(): array {
+        return [
+            ['0.0', 0.0], ['0.125', 1/8], ['0.25', 1/4], ['0.5', 1/2],
+            ['0.75', 3/4], ['1.0', 1.0], ['1.25', 1.25], ['1.5', 1.5],
+            ['2.5', 2.5], ['2.75', 2.75],
+        ];
+    }
+
+    /**
+     * Provide fraction string and float data.
+     *
+     * @see \Tests\Unit\Support\NumberTest::testFloatFromString()
+     * @see \Tests\Unit\Support\NumberTest::testFractionStringFromFloat()
+     */
+    public function fractionStringFloatsProvider(): array {
+        return [
+            ['0', 0.0], ['1/8', 1/8], ['1/4', 1/4], ['1/3', 1/3], ['1/2', 1/2],
+            ['2/3', 2/3], ['3/4', 3/4], ['1', 1.0], ['1 1/4', 1.25],
+            ['1 1/2', 1.5], ['2 1/2', 2.5], ['2 3/4', 2.75],
+        ];
+    }
+}