diff --git a/tests/phpunit/tests/actions.php b/tests/phpunit/tests/actions.php
index ebfd6dad5a..9bafdcadd6 100644
--- a/tests/phpunit/tests/actions.php
+++ b/tests/phpunit/tests/actions.php
@@ -144,8 +144,8 @@ class Tests_Actions extends WP_UnitTestCase {
 	}
 
 	function test_did_action() {
-		$tag1 = rand_str();
-		$tag2 = rand_str();
+		$tag1 = 'action1';
+		$tag2 = 'action2';
 
 		// do action tag1 but not tag2
 		do_action($tag1);
diff --git a/tests/phpunit/tests/admin/includesScreen.php b/tests/phpunit/tests/admin/includesScreen.php
index 1805d2db03..317be9bac0 100644
--- a/tests/phpunit/tests/admin/includesScreen.php
+++ b/tests/phpunit/tests/admin/includesScreen.php
@@ -186,7 +186,7 @@ class Tests_Admin_includesScreen extends WP_UnitTestCase {
 	 * @ticket 19828
 	 */
 	function test_help_tabs_priority() {
-		$tab_1      = rand_str();
+		$tab_1      = 'tab1';
 		$tab_1_args = array(
 			'title'    => 'Help!',
 			'id'       => $tab_1,
@@ -195,7 +195,7 @@ class Tests_Admin_includesScreen extends WP_UnitTestCase {
 			'priority' => 10,
 		);
 
-		$tab_2      = rand_str();
+		$tab_2      = 'tab2';
 		$tab_2_args = array(
 			'title'    => 'Help!',
 			'id'       => $tab_2,
@@ -203,7 +203,7 @@ class Tests_Admin_includesScreen extends WP_UnitTestCase {
 			'callback' => false,
 			'priority' => 2,
 		);
-		$tab_3      = rand_str();
+		$tab_3      = 'tab3';
 		$tab_3_args = array(
 			'title'    => 'help!',
 			'id'       => $tab_3,
@@ -211,7 +211,7 @@ class Tests_Admin_includesScreen extends WP_UnitTestCase {
 			'callback' => false,
 			'priority' => 40,
 		);
-		$tab_4      = rand_str();
+		$tab_4      = 'tab4';
 		$tab_4_args = array(
 			'title'    => 'help!',
 			'id'       => $tab_4,
diff --git a/tests/phpunit/tests/cron.php b/tests/phpunit/tests/cron.php
index b411a5be1e..ecd60be402 100644
--- a/tests/phpunit/tests/cron.php
+++ b/tests/phpunit/tests/cron.php
@@ -39,16 +39,16 @@ class Tests_Cron extends WP_UnitTestCase {
 
 	function test_schedule_event_single_args() {
 		// schedule an event with arguments and make sure it's returned by wp_next_scheduled
-		$hook = rand_str();
+		$hook = 'event';
 		$timestamp = strtotime('+1 hour');
-		$args = array(rand_str());
+		$args = array('foo');
 
 		wp_schedule_single_event( $timestamp, $hook, $args );
 		// this returns the timestamp only if we provide matching args
 		$this->assertEquals( $timestamp, wp_next_scheduled($hook, $args) );
 		// these don't match so return nothing
 		$this->assertEquals( false, wp_next_scheduled($hook) );
-		$this->assertEquals( false, wp_next_scheduled($hook, array(rand_str())) );
+		$this->assertEquals( false, wp_next_scheduled($hook, array('bar')) );
 
 		// it's a non recurring event
 		$this->assertEquals( '', wp_get_schedule($hook, $args) );
@@ -69,17 +69,17 @@ class Tests_Cron extends WP_UnitTestCase {
 
 	function test_schedule_event_args() {
 		// schedule an event and make sure it's returned by wp_next_scheduled
-		$hook = rand_str();
+		$hook = 'event';
 		$timestamp = strtotime('+1 hour');
 		$recur = 'hourly';
-		$args = array(rand_str());
+		$args = array('foo');
 
 		wp_schedule_event( $timestamp, 'hourly', $hook, $args );
 		// this returns the timestamp only if we provide matching args
 		$this->assertEquals( $timestamp, wp_next_scheduled($hook, $args) );
 		// these don't match so return nothing
 		$this->assertEquals( false, wp_next_scheduled($hook) );
-		$this->assertEquals( false, wp_next_scheduled($hook, array(rand_str())) );
+		$this->assertEquals( false, wp_next_scheduled($hook, array('bar')) );
 
 		$this->assertEquals( $recur, wp_get_schedule($hook, $args) );
 
diff --git a/tests/phpunit/tests/db/charset.php b/tests/phpunit/tests/db/charset.php
index 97d9b26b7d..f8591c260f 100644
--- a/tests/phpunit/tests/db/charset.php
+++ b/tests/phpunit/tests/db/charset.php
@@ -543,8 +543,8 @@ class Tests_DB_Charset extends WP_UnitTestCase {
 		$table_name = 'test_get_table_charset';
 
 		$vars = array();
-		foreach( $this->table_and_column_defs as $value ) {
-			$this_table_name = $table_name . '_' . rand_str( 5 );
+		foreach( $this->table_and_column_defs as $i => $value ) {
+			$this_table_name = $table_name . '_' . $i;
 			$drop = "DROP TABLE IF EXISTS $this_table_name";
 			$create = "CREATE TABLE $this_table_name {$value['definition']}";
 			$vars[] = array( $drop, $create, $this_table_name, $value['table_expected'] );
@@ -583,8 +583,8 @@ class Tests_DB_Charset extends WP_UnitTestCase {
 		$table_name = 'test_get_column_charset';
 
 		$vars = array();
-		foreach( $this->table_and_column_defs as $value ) {
-			$this_table_name = $table_name . '_' . rand_str( 5 );
+		foreach( $this->table_and_column_defs as $i => $value ) {
+			$this_table_name = $table_name . '_' . $i;
 			$drop = "DROP TABLE IF EXISTS $this_table_name";
 			$create = "CREATE TABLE $this_table_name {$value['definition']}";
 			$vars[] = array( $drop, $create, $this_table_name, $value['column_expected'] );
@@ -687,8 +687,8 @@ class Tests_DB_Charset extends WP_UnitTestCase {
 			),
 		);
 
-		foreach( $data as &$value ) {
-			$this_table_name = $table_name . '_' . rand_str( 5 );
+		foreach( $data as $i => &$value ) {
+			$this_table_name = $table_name . '_' . $i;
 
 			$value[0] = "CREATE TABLE $this_table_name {$value[0]}";
 			$value[1] = "INSERT INTO $this_table_name VALUES {$value[1]}";
@@ -801,8 +801,8 @@ class Tests_DB_Charset extends WP_UnitTestCase {
 			),
 		);
 
-		foreach( $data as &$value ) {
-			$this_table_name = $table_name . '_' . rand_str( 5 );
+		foreach( $data as $i => &$value ) {
+			$this_table_name = $table_name . '_' . $i;
 
 			$value[0] = "CREATE TABLE $this_table_name {$value[0]}";
 			$value[2] = "SELECT * FROM $this_table_name WHERE a='\xf0\x9f\x98\x88'";
diff --git a/tests/phpunit/tests/option/option.php b/tests/phpunit/tests/option/option.php
index a02f8d1bcf..fea674dd53 100644
--- a/tests/phpunit/tests/option/option.php
+++ b/tests/phpunit/tests/option/option.php
@@ -10,10 +10,10 @@ class Tests_Option_Option extends WP_UnitTestCase {
 	}
 
 	function test_the_basics() {
-		$key = rand_str();
-		$key2 = rand_str();
-		$value = rand_str();
-		$value2 = rand_str();
+		$key = 'key1';
+		$key2 = 'key2';
+		$value = 'value1';
+		$value2 = 'value2';
 
 		$this->assertFalse( get_option( 'doesnotexist' ) );
 		$this->assertTrue( add_option( $key, $value ) );
@@ -35,7 +35,7 @@ class Tests_Option_Option extends WP_UnitTestCase {
 	}
 
 	function test_default_filter() {
-		$random = rand_str();
+		$value = 'value';
 
 		$this->assertFalse( get_option( 'doesnotexist' ) );
 
@@ -48,10 +48,10 @@ class Tests_Option_Option extends WP_UnitTestCase {
 		$this->assertEquals( 'bar', get_option( 'doesnotexist', 'bar' ) );
 
 		// Once the option exists, the $default arg and the default filter are ignored.
-		add_option( 'doesnotexist', $random );
-		$this->assertEquals( $random, get_option( 'doesnotexist', 'foo' ) );
+		add_option( 'doesnotexist', $value );
+		$this->assertEquals( $value, get_option( 'doesnotexist', 'foo' ) );
 		add_filter( 'default_option_doesnotexist', array( $this, '__return_foo' ) );
-		$this->assertEquals( $random, get_option( 'doesnotexist', 'foo' ) );
+		$this->assertEquals( $value, get_option( 'doesnotexist', 'foo' ) );
 		remove_filter( 'default_option_doesnotexist', array( $this, '__return_foo' ) );
 
 		// Cleanup
diff --git a/tests/phpunit/tests/option/siteOption.php b/tests/phpunit/tests/option/siteOption.php
index 8d76399d8c..b5f178c734 100644
--- a/tests/phpunit/tests/option/siteOption.php
+++ b/tests/phpunit/tests/option/siteOption.php
@@ -92,9 +92,9 @@ class Tests_Option_SiteOption extends WP_UnitTestCase {
 	}
 
 	function test_update_site_option_returns_true_for_new_value() {
-		$key = rand_str();
-		$value = rand_str();
-		$new_value = rand_str();
+		$key = 'key';
+		$value = 'value1';
+		$new_value = 'value2';
 		add_site_option( $key, $value );
 		$this->assertTrue( update_site_option( $key, $new_value ) );
 	}
diff --git a/tests/phpunit/tests/option/siteTransient.php b/tests/phpunit/tests/option/siteTransient.php
index 62cf77512a..29aab46ac6 100644
--- a/tests/phpunit/tests/option/siteTransient.php
+++ b/tests/phpunit/tests/option/siteTransient.php
@@ -14,9 +14,9 @@ class Tests_Option_SiteTransient extends WP_UnitTestCase {
 	}
 
 	function test_the_basics() {
-		$key = rand_str();
-		$value = rand_str();
-		$value2 = rand_str();
+		$key = 'key1';
+		$value = 'value1';
+		$value2 = 'value2';
 
 		$this->assertFalse( get_site_transient( 'doesnotexist' ) );
 		$this->assertTrue( set_site_transient( $key, $value ) );
diff --git a/tests/phpunit/tests/option/transient.php b/tests/phpunit/tests/option/transient.php
index 759a9b4f7e..f946852b03 100644
--- a/tests/phpunit/tests/option/transient.php
+++ b/tests/phpunit/tests/option/transient.php
@@ -14,9 +14,9 @@ class Tests_Option_Transient extends WP_UnitTestCase {
 	}
 
 	function test_the_basics() {
-		$key = rand_str();
-		$value = rand_str();
-		$value2 = rand_str();
+		$key = 'key1';
+		$value = 'value1';
+		$value2 = 'value2';
 
 		$this->assertFalse( get_transient( 'doesnotexist' ) );
 		$this->assertTrue( set_transient( $key, $value ) );
diff --git a/tests/phpunit/tests/query/results.php b/tests/phpunit/tests/query/results.php
index fa544319b1..40fe44759c 100644
--- a/tests/phpunit/tests/query/results.php
+++ b/tests/phpunit/tests/query/results.php
@@ -456,17 +456,17 @@ class Tests_Query_Results extends WP_UnitTestCase {
 	 * @ticket 16854
 	 */
 	function test_query_author_vars() {
-		$author_1 = self::factory()->user->create( array( 'user_login' => 'admin1', 'user_pass' => rand_str(), 'role' => 'author' ) );
-		$post_1 = self::factory()->post->create( array( 'post_title' => rand_str(), 'post_author' => $author_1, 'post_date' => '2007-01-01 00:00:00' ) );
+		$author_1 = self::factory()->user->create( array( 'user_login' => 'author1', 'role' => 'author' ) );
+		$post_1 = self::factory()->post->create( array( 'post_title' => 'Post 1', 'post_author' => $author_1, 'post_date' => '2007-01-01 00:00:00' ) );
 
-		$author_2 = self::factory()->user->create( array( 'user_login' => rand_str(), 'user_pass' => rand_str(), 'role' => 'author' ) );
-		$post_2 = self::factory()->post->create( array( 'post_title' => rand_str(), 'post_author' => $author_2, 'post_date' => '2007-01-01 00:00:00' ) );
+		$author_2 = self::factory()->user->create( array( 'user_login' => 'author2', 'role' => 'author' ) );
+		$post_2 = self::factory()->post->create( array( 'post_title' => 'Post 2', 'post_author' => $author_2, 'post_date' => '2007-01-01 00:00:00' ) );
 
-		$author_3 = self::factory()->user->create( array( 'user_login' => rand_str(), 'user_pass' => rand_str(), 'role' => 'author' ) );
-		$post_3 = self::factory()->post->create( array( 'post_title' => rand_str(), 'post_author' => $author_3, 'post_date' => '2007-01-01 00:00:00' ) );
+		$author_3 = self::factory()->user->create( array( 'user_login' => 'author3', 'role' => 'author' ) );
+		$post_3 = self::factory()->post->create( array( 'post_title' => 'Post 3', 'post_author' => $author_3, 'post_date' => '2007-01-01 00:00:00' ) );
 
-		$author_4 = self::factory()->user->create( array( 'user_login' => rand_str(), 'user_pass' => rand_str(), 'role' => 'author' ) );
-		$post_4 = self::factory()->post->create( array( 'post_title' => rand_str(), 'post_author' => $author_4, 'post_date' => '2007-01-01 00:00:00' ) );
+		$author_4 = self::factory()->user->create( array( 'user_login' => 'author4', 'role' => 'author' ) );
+		$post_4 = self::factory()->post->create( array( 'post_title' => 'Post 4', 'post_author' => $author_4, 'post_date' => '2007-01-01 00:00:00' ) );
 
 		$posts = $this->q->query( array(
 			'author' => '',
@@ -549,7 +549,7 @@ class Tests_Query_Results extends WP_UnitTestCase {
 		$this->assertEqualSets( array( $author_3, $author_4 ), $author_ids );
 
 		$posts = $this->q->query( array(
-			'author_name' => 'admin1',
+			'author_name' => 'author1',
 			'post__in' => array( $post_1, $post_2, $post_3, $post_4 )
 		) );
 		$author_ids = array_unique( wp_list_pluck( $posts, 'post_author' ) );
diff --git a/tests/phpunit/tests/term/getTerms.php b/tests/phpunit/tests/term/getTerms.php
index 1537370332..6d199c0747 100644
--- a/tests/phpunit/tests/term/getTerms.php
+++ b/tests/phpunit/tests/term/getTerms.php
@@ -2314,8 +2314,8 @@ class Tests_Term_getTerms extends WP_UnitTestCase {
 
 	protected function set_up_three_posts_and_tags() {
 		$posts = self::factory()->post->create_many( 3, array( 'post_type' => 'post' ) );
-		foreach ( $posts as $post ) {
-			wp_set_object_terms( $post, rand_str(), 'post_tag' );
+		foreach ( $posts as $i => $post ) {
+			wp_set_object_terms( $post, "term_{$i}", 'post_tag' );
 		}
 
 		wp_cache_delete( 'last_changed', 'terms' );
diff --git a/tests/phpunit/tests/term/wpInsertTerm.php b/tests/phpunit/tests/term/wpInsertTerm.php
index f636092095..fd219f5e70 100644
--- a/tests/phpunit/tests/term/wpInsertTerm.php
+++ b/tests/phpunit/tests/term/wpInsertTerm.php
@@ -10,7 +10,7 @@ class Tests_Term_WpInsertTerm extends WP_UnitTestCase {
 		_clean_term_filters();
 		// insert one term into every post taxonomy
 		// otherwise term_ids and term_taxonomy_ids might be identical, which could mask bugs
-		$term = rand_str();
+		$term = 'seed_term';
 		foreach(get_object_taxonomies('post') as $tax)
 			wp_insert_term( $term, $tax );
 	}
@@ -20,7 +20,7 @@ class Tests_Term_WpInsertTerm extends WP_UnitTestCase {
 		register_taxonomy( $taxonomy, 'post' );
 
 		// a new unused term
-		$term = rand_str();
+		$term = 'term';
 		$this->assertNull( term_exists($term) );
 
 		$initial_count = wp_count_terms( $taxonomy );
diff --git a/tests/phpunit/tests/term/wpSetObjectTerms.php b/tests/phpunit/tests/term/wpSetObjectTerms.php
index f14516b119..248c7bf28e 100644
--- a/tests/phpunit/tests/term/wpSetObjectTerms.php
+++ b/tests/phpunit/tests/term/wpSetObjectTerms.php
@@ -110,7 +110,7 @@ class Tests_Term_WpSetObjectTerms extends WP_UnitTestCase {
 
 		$terms = array();
 		for ($i=0; $i<3; $i++ ) {
-			$term = rand_str();
+			$term = "term_{$i}";
 			$result = wp_insert_term( $term, $this->taxonomy );
 			$this->assertInternalType( 'array', $result );
 			$term_id[$term] = $result['term_id'];
@@ -245,7 +245,7 @@ class Tests_Term_WpSetObjectTerms extends WP_UnitTestCase {
 		// first set: 3 terms
 		$terms_1 = array();
 		for ($i=0; $i<3; $i++ ) {
-			$term = rand_str();
+			$term = "term_{$i}";
 			$result = wp_insert_term( $term, $this->taxonomy );
 			$this->assertInternalType( 'array', $result );
 			$terms_1[$i] = $result['term_id'];
@@ -255,7 +255,7 @@ class Tests_Term_WpSetObjectTerms extends WP_UnitTestCase {
 		$terms_2 = array();
 		$terms_2[0] = $terms_1[1];
 
-		$term = rand_str();
+		$term = 'term';
 		$result = wp_insert_term( $term, $this->taxonomy );
 		$terms_2[1] = $result['term_id'];
 
diff --git a/tests/phpunit/tests/user.php b/tests/phpunit/tests/user.php
index 481fe6922e..a114e8fc2f 100644
--- a/tests/phpunit/tests/user.php
+++ b/tests/phpunit/tests/user.php
@@ -103,8 +103,8 @@ class Tests_User extends WP_UnitTestCase {
 
 	// simple tests for usermeta functions
 	function test_usermeta() {
-		$key = rand_str();
-		$val = rand_str();
+		$key = 'key';
+		$val = 'value1';
 
 		// get a meta key that doesn't exist
 		$this->assertEquals( '', get_user_meta( self::$author_id, $key, true ) );
@@ -114,7 +114,7 @@ class Tests_User extends WP_UnitTestCase {
 		$this->assertEquals( $val, get_user_meta( self::$author_id, $key, true ) );
 
 		// change and get again
-		$val2 = rand_str();
+		$val2 = 'value2';
 		update_user_meta( self::$author_id, $key, $val2 );
 		$this->assertEquals( $val2, get_user_meta( self::$author_id, $key, true ) );
 
@@ -581,14 +581,14 @@ class Tests_User extends WP_UnitTestCase {
 	 */
 	function test_user_update_email_error() {
 		$id1 = wp_insert_user( array(
-			'user_login' => rand_str(),
+			'user_login' => 'blackburn',
 			'user_pass'  => 'password',
 			'user_email' => 'blackburn@battlefield4.com',
 		) );
 		$this->assertEquals( $id1, email_exists( 'blackburn@battlefield4.com' ) );
 
 		$id2 = wp_insert_user( array(
-			'user_login' => rand_str(),
+			'user_login' => 'miller',
 			'user_pass'  => 'password',
 			'user_email' => 'miller@battlefield4.com',
 		) );
diff --git a/tests/phpunit/tests/xmlrpc/wp/getPosts.php b/tests/phpunit/tests/xmlrpc/wp/getPosts.php
index 3d8dff4bdb..3119fea61f 100644
--- a/tests/phpunit/tests/xmlrpc/wp/getPosts.php
+++ b/tests/phpunit/tests/xmlrpc/wp/getPosts.php
@@ -136,11 +136,11 @@ class Tests_XMLRPC_wp_getPosts extends WP_XMLRPC_UnitTestCase {
 	function test_search() {
 		$this->make_user_by_role( 'editor' );
 
-		$post_ids[] = self::factory()->post->create( array( 'post_title' => 'First: ' . rand_str() ) );
-		$post_ids[] = self::factory()->post->create( array( 'post_title' => 'Second: ' . rand_str() ) );
+		$post_ids[] = self::factory()->post->create( array( 'post_title' => 'First: Hello, World!' ) );
+		$post_ids[] = self::factory()->post->create( array( 'post_title' => 'Second: Hello, World!' ) );
 
 		// Search for none of them
-		$filter = array( 's' => rand_str() );
+		$filter = array( 's' => 'Third' );
 		$results = $this->myxmlrpcserver->wp_getPosts( array( 1, 'editor', 'editor', $filter ) );
 		$this->assertNotInstanceOf( 'IXR_Error', $results );
 		$this->assertEquals( 0, count( $results ) );
diff --git a/tests/phpunit/tests/xmlrpc/wp/getTerms.php b/tests/phpunit/tests/xmlrpc/wp/getTerms.php
index e5c633615f..794c709d53 100644
--- a/tests/phpunit/tests/xmlrpc/wp/getTerms.php
+++ b/tests/phpunit/tests/xmlrpc/wp/getTerms.php
@@ -66,7 +66,7 @@ class Tests_XMLRPC_wp_getTerms extends WP_XMLRPC_UnitTestCase {
 		$num_terms = 12;
 		register_taxonomy( $tax_name, 'post' );
 		for( $i = 0; $i < $num_terms; $i++ )
-			wp_insert_term( rand_str( 10 ), $tax_name );
+			wp_insert_term( "term_{$i}", $tax_name );
 
 
 		// test fetching all terms
diff --git a/tests/phpunit/tests/xmlrpc/wp/newPost.php b/tests/phpunit/tests/xmlrpc/wp/newPost.php
index a8dae54e6e..3092aef637 100644
--- a/tests/phpunit/tests/xmlrpc/wp/newPost.php
+++ b/tests/phpunit/tests/xmlrpc/wp/newPost.php
@@ -233,11 +233,11 @@ class Tests_XMLRPC_wp_newPost extends WP_XMLRPC_UnitTestCase {
 	function test_terms() {
 		$this->make_user_by_role( 'editor' );
 
-		$tag1 = wp_create_tag ( rand_str( 30 ) );
+		$tag1 = wp_create_tag( 'tag1' );
 		$this->assertInternalType( 'array', $tag1 );
-		$tag2 = wp_create_tag ( rand_str( 30 ) );
+		$tag2 = wp_create_tag( 'tag2' );
 		$this->assertInternalType( 'array', $tag2 );
-		$tag3 = wp_create_tag ( rand_str( 30 ) );
+		$tag3 = wp_create_tag( 'tag3' );
 		$this->assertInternalType( 'array', $tag3 );
 
 		$post = array(
@@ -258,13 +258,13 @@ class Tests_XMLRPC_wp_newPost extends WP_XMLRPC_UnitTestCase {
 	function test_terms_names() {
 		$this->make_user_by_role( 'editor' );
 
-		$ambiguous_name = rand_str( 30 );
+		$ambiguous_name = 'foo';
 		$parent_cat = wp_create_category( $ambiguous_name );
 		$child_cat = wp_create_category( $ambiguous_name, $parent_cat );
 
-		$cat1_name = rand_str( 30 );
+		$cat1_name = 'cat1';
 		$cat1 = wp_create_category( $cat1_name, $parent_cat );
-		$cat2_name = rand_str( 30 );
+		$cat2_name = 'cat2';
 
 		// first a post with valid categories; one that already exists and one to be created
 		$post = array(