diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f3b59ea..6fb06d8 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -20,9 +20,9 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  sniff:
+  lint:
     runs-on: ubuntu-latest
-    name: Sniff
+    name: Lint
 
     steps:
       - name: Checkout code
@@ -37,7 +37,7 @@ jobs:
         uses: ramsey/composer-install@v3
 
       - name: Analyze source code
-        run: composer sniff
+        run: composer lint
 
   analyze:
     runs-on: ubuntu-latest
@@ -59,7 +59,7 @@ jobs:
         run: composer analyze
 
   test:
-    needs: [sniff, analyze]
+    needs: [lint, analyze]
     runs-on: ubuntu-latest
     name: Test
 
@@ -83,5 +83,15 @@ jobs:
       - name: Install PHP dependencies
         uses: ramsey/composer-install@v3
 
-      - name: Run test
+      - name: Install bashunit
+        run: |
+          curl -s https://bashunit.typeddevs.com/install.sh > install.sh
+          chmod +x install.sh
+          ./install.sh
+
+      - name: Run PHPUnit test
         run: composer test
+
+      - name: Run bashunit test
+        if: matrix.machine != 'windows-latest'
+        run: ./lib/bashunit ./tests/bashunit/*.sh
diff --git a/composer.json b/composer.json
index 5984915..1a984f4 100644
--- a/composer.json
+++ b/composer.json
@@ -57,7 +57,7 @@
 	"scripts": {
 		"analyze": "phpstan",
 		"format": "phpcbf",
-		"sniff": "phpcs",
+		"lint": "phpcs",
 		"test": "phpunit"
 	},
 	"config": {
diff --git a/tests/bashunit/test_eq.sh b/tests/bashunit/test_eq.sh
new file mode 100644
index 0000000..569d6f6
--- /dev/null
+++ b/tests/bashunit/test_eq.sh
@@ -0,0 +1,29 @@
+# @data_provider data_equal
+function test_equal() {
+	bin/version eq $1 $2 2>&1
+  	local exit_code=$?
+
+	assert_equals 0 $exit_code;
+}
+
+# @data_provider data_not_equal
+function test_not_equal() {
+	bin/version eq $1 $2 2>&1
+  	local exit_code=$?
+
+	assert_equals 1 $exit_code;
+}
+
+function data_not_equal() {
+	echo "1.0.0" "1.0.1";
+	echo "v2.0.0" "v2.1.0";
+	echo "3.5.2-alpha.1" "3.5.2-alpha.2";
+}
+
+function data_equal() {
+	echo "1.0.0" "1.0.0";
+	echo "v2.0.0" "v2.0.0";
+	echo "3.5.1-alpha.1" "3.5.1-alpha.1";
+	echo "4.0.0-beta.2+1" "4.0.0-beta.2+2"; # Build metadata should not affect equality.
+	echo "4.2.0-beta.2+1" "4.2.0-beta.2+1";
+}
diff --git a/tests/bashunit/test_gt.sh b/tests/bashunit/test_gt.sh
new file mode 100644
index 0000000..5b7a7a5
--- /dev/null
+++ b/tests/bashunit/test_gt.sh
@@ -0,0 +1,28 @@
+# @data_provider data_greater_than
+function test_greater_than() {
+	bin/version gt $1 $2 2>&1
+  	local exit_code=$?
+
+	assert_equals 0 $exit_code;
+}
+
+# @data_provider data_not_greater_than
+function test_not_greater_than() {
+	bin/version gt $1 $2 2>&1
+  	local exit_code=$?
+
+	assert_equals 1 $exit_code;
+}
+
+function data_not_greater_than() {
+	echo "1.0.0" "1.0.0"; # Equal.
+	echo "v2.0.0" "v2.1.0"; # Less than.
+	echo "3.5.2-alpha.1" "3.5.2-alpha.2"; # Less than with pre-release.
+	echo "3.5.2-alpha.2+2" "3.5.2-alpha.2+1";
+}
+
+function data_greater_than() {
+	echo "1.0.1" "1.0.0"; # Greater than.
+	echo "v2.1.0" "v2.0.0"; # Greater than with prefix.
+	echo "3.5.2-alpha.2" "3.5.2-alpha.1"; # Greater than with pre-release.
+}
diff --git a/tests/bashunit/test_increment.sh b/tests/bashunit/test_increment.sh
new file mode 100644
index 0000000..e527c7c
--- /dev/null
+++ b/tests/bashunit/test_increment.sh
@@ -0,0 +1,60 @@
+# @data_provider data_increment_patch
+function test_increment_patch() {
+	ver=$(bin/version increment $1);
+	assert_equals $ver $2;
+}
+
+# @data_provider data_increment_minor
+function test_increment_minor() {
+	ver=$(bin/version increment $1 --part minor);
+	assert_equals $ver $2;
+}
+
+# @data_provider data_increment_major
+function test_increment_major() {
+	ver=$(bin/version increment $1 --part major);
+	assert_equals $ver $2;
+}
+
+# @data_provider data_increment_with_pre_release
+function test_increment_with_pre_release() {
+	ver=$(bin/version increment $1 --pre alpha);
+	assert_equals $ver $2;
+}
+
+# @data_provider data_increment_with_build
+function test_increment_with_build() {
+	ver=$(bin/version increment $1 --build 123);
+	assert_equals $ver $2;
+}
+
+# @data_provider data_increment_with_pre_release_and_build
+function test_increment_with_pre_release_and_build() {
+	ver=$(bin/version increment $1 --build 123 --pre alpha);
+	assert_equals $ver $2;
+}
+
+function data_increment_patch() {
+	echo "0.0.0" "0.0.1";
+	echo "1.0.0" "1.0.1";
+}
+
+function data_increment_minor() {
+	echo "0.0.0" "0.1.0";
+	echo "1.0.0" "1.1.0";
+}
+
+function data_increment_major() {
+	echo "0.0.0" "1.0.0";
+	echo "1.0.0" "2.0.0";
+}
+
+function data_increment_with_pre_release() {
+	echo "0.0.0" "0.0.1-alpha";
+	echo "1.0.0" "1.0.1-alpha";
+}
+
+function data_increment_with_pre_release_and_build() {
+	echo "0.0.0" "0.0.1-alpha+123";
+	echo "1.0.0" "1.0.1-alpha+123";
+}
diff --git a/tests/bashunit/test_lt.sh b/tests/bashunit/test_lt.sh
new file mode 100644
index 0000000..ba4e83b
--- /dev/null
+++ b/tests/bashunit/test_lt.sh
@@ -0,0 +1,27 @@
+# @data_provider data_less_than
+function test_less_than() {
+	bin/version lt $1 $2 2>&1
+  	local exit_code=$?
+
+	assert_equals 0 $exit_code;
+}
+
+# @data_provider data_not_less_than
+function test_not_less_than() {
+	bin/version lt $1 $2 2>&1
+  	local exit_code=$?
+
+	assert_equals 1 $exit_code;
+}
+
+function data_less_than() {
+	echo "1.0.0" "1.0.1";
+	echo "v2.0.0" "v2.1.0";
+	echo "3.5.2-alpha.1" "3.5.2-alpha.2";
+}
+
+function data_not_less_than() {
+	echo "1.0.0" "1.0.0"; # Equal.
+	echo "v2.0.0" "v1.0.0"; # Greater than.
+	echo "3.5.1-alpha.2" "3.5.1-alpha.1"; # Greater than with pre-release.
+}
diff --git a/tests/bashunit/test_validate.sh b/tests/bashunit/test_validate.sh
new file mode 100644
index 0000000..63097a8
--- /dev/null
+++ b/tests/bashunit/test_validate.sh
@@ -0,0 +1,32 @@
+# @data_provider data_valid
+function test_equal() {
+	bin/version validate $1 2>&1
+  	local exit_code=$?
+
+	assert_equals 0 $exit_code;
+}
+
+# @data_provider data_invalid
+function test_invalid() {
+	bin/version validate $1 2>&1
+  	local exit_code=$?
+
+	assert_equals 1 $exit_code;
+}
+
+function data_valid() {
+	echo "1.0.0"
+	echo "v1.0.0"
+	echo "2.1.7-alpha"
+	echo "1.0.0-beta.1"
+	echo "3.4.5+build.78"
+	echo "0.9.1-alpha.1+exp.sha.5114f85"
+}
+
+function data_invalid() {
+	echo "0"
+	echo "0.0"
+	echo "v"
+	echo "v0"
+	echo "v0.0"
+}
diff --git a/tests/phpunit/Commands/ValidateCommandTest.php b/tests/phpunit/Commands/ValidateCommandTest.php
index 823782d..18d0e01 100644
--- a/tests/phpunit/Commands/ValidateCommandTest.php
+++ b/tests/phpunit/Commands/ValidateCommandTest.php
@@ -47,6 +47,8 @@ public function testValidVersionArgument(string $version): void
 
 	public static function dataInvalidVersionArgument(): iterable
 	{
+		yield ['0'];
+		yield ['0.0'];
 		yield ['v'];
 		yield ['v0'];
 		yield ['v0.0'];