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At this time you should add term in little bit another way (in compare with this answer) First of all in your file begin you should write

use Drupal\taxonomy\Entity\Term;

Because Term class listed in Drupal\taxonomy\Entity. And you don't need to pass taxonomy_term parametr to

Term::create

because only one parametr is needed (array with values) (below listed code for this method in taxonomy module)

public function create(array $values = array()) {
  // Save new terms with no parents by default.
  if (empty($values['parent'])) {
    $values['parent'] = array(0);
  }
  $entity = parent::create($values);
  return $entity;
}

So the final example is

use Drupal\taxonomy\Entity\Term;
$categories_vocabulary = 'blog_categories'; // Vocabulary machine name
$categories = ['test 1', 'test 2', 'test 3', 'test 4']; // List of test terms
foreach ($categories as $category) {
  $term = Term::create(array(
    'parent' => array(),
    'name' => $category,
    'vid' => $categories_vocabulary,
))->save();

At this time you should add term in little bit another way (in compare with this answer) First of all in your file begin you should write

use Drupal\taxonomy\Entity\Term;

Because Term class listed in Drupal\taxonomy\Entity. And you don't need to pass taxonomy_term parametr to

Term::create

because only one parametr is needed (array with values) (below listed code for this method in taxonomy module)

public function create(array $values = array()) {
  // Save new terms with no parents by default.
  if (empty($values['parent'])) {
    $values['parent'] = array(0);
  }
  $entity = parent::create($values);
  return $entity;
}

So the final example is

use Drupal\taxonomy\Entity\Term;
$categories_vocabulary = 'blog_categories'; // Vocabulary machine name
$categories = ['test 1', 'test 2', 'test 3', 'test 4']; // List of test terms
foreach ($categories as $category) {
  $term = Term::create(array(
    'parent' => array(),
    'name' => $category,
    'vid' => $categories_vocabulary,
  ))->save();
}

At this time you should add term in little bit another way (in compare with this answer) First of all in your file begin you should write

use Drupal\taxonomy\Entity\Term;

Because Term class listed in Drupal\taxonomy\Entity. And you don't need to pass taxonomy_term parametr to

Term::create

because only one parametr is needed (array with values) (below listed code for this method in taxonomy module)

public function create(array $values = array()) {
  // Save new terms with no parents by default.
  if (empty($values['parent'])) {
    $values['parent'] = array(0);
  }
  $entity = parent::create($values);
  return $entity;
}

So the final example is

use Drupal\taxonomy\Entity\Term;
$categories_vocabulary = 'blog_categories'; // Vocabulary machine name
$categories = ['test 1', 'test 2', 'test 3', 'test 4']; // List of test terms
foreach ($categories as $category) {
  $term = Term::create(array(
    'parent' => array(),
    'name' => $category,
    'vid' => $categories_vocabulary,
))->save();

At this time you should add term in little bit another way (in compare with this answer) First of all in your file begin you should write

use Drupal\taxonomy\Entity\Term;

Because Term class listed in Drupal\taxonomy\Entity. And you don't need to pass taxonomy_term parametr to

Term::create

because only one parametr is needed (array with values) (below listed code for this method in taxonomy module)

public function create(array $values = array()) {
  // Save new terms with no parents by default.
  if (empty($values['parent'])) {
    $values['parent'] = array(0);
  }
  $entity = parent::create($values);
  return $entity;
}

So the final example is

use Drupal\taxonomy\Entity\Term;
$categories_vocabulary = 'blog_categories'; // Vocabulary machine name
$categories = ['test 1', 'test 2', 'test 3', 'test 4']; // List of test terms
foreach ($categories as $category) {
  $term = Term::create(array(
    'parent' => array(),
    'name' => $category,
    'vid' => $categories_vocabulary,
))->save();

At this time you should add term in little bit another way (in compare with this answer) First of all in your file begin you should write

use Drupal\taxonomy\Entity\Term;

Because Term class listed in Drupal\taxonomy\Entity. And you don't need to pass taxonomy_term parametr to

Term::create

because only one parametr is needed (array with values) (below listed code for this method in taxonomy module)

public function create(array $values = array()) {
// Save new terms with no parents by default.
if (empty($values['parent'])) {
  $values['parent'] = array(0);
}
$entity = parent::create($values);
return $entity;
}

So the final example is

use Drupal\taxonomy\Entity\Term;
$categories_vocabulary = 'blog_categories'; // Vocabulary vid
$categories = ['test 1', 'test 2', 'test 3', 'test 4']; // List of test terms
foreach ($categories as $category) {
  $term = Term::create(array(
    'parent' => array(),
    'name' => $category,
    'vid' => $categories_vocabulary,
))->save();
}

At this time you should add term in little bit another way (in compare with this answer) First of all in your file begin you should write

use Drupal\taxonomy\Entity\Term;

Because Term class listed in Drupal\taxonomy\Entity. And you don't need to pass taxonomy_term parametr to

Term::create

because only one parametr is needed (array with values) (below listed code for this method in taxonomy module)

public function create(array $values = array()) {
  // Save new terms with no parents by default.
  if (empty($values['parent'])) {
    $values['parent'] = array(0);
  }
  $entity = parent::create($values);
  return $entity;
}

So the final example is

use Drupal\taxonomy\Entity\Term;
$categories_vocabulary = 'blog_categories'; // Vocabulary machine name
$categories = ['test 1', 'test 2', 'test 3', 'test 4']; // List of test terms
foreach ($categories as $category) {
  $term = Term::create(array(
    'parent' => array(),
    'name' => $category,
    'vid' => $categories_vocabulary,
))->save();