diff --git a/test/dbm/test_dbm.rb b/test/dbm/test_dbm.rb
index 9d63bdf5b32e2f..c7ca50cd090784 100644
--- a/test/dbm/test_dbm.rb
+++ b/test/dbm/test_dbm.rb
@@ -87,7 +87,7 @@ def test_s_open_with_block
     end
     def test_s_open_lock
       return unless have_fork?	# snip this test
-      fork() {
+      pid = fork() {
         assert_instance_of(DBM, dbm = DBM.open("tmptest_dbm", 0644))
         sleep 2
       }
@@ -101,7 +101,7 @@ def test_s_open_lock
           end
         }
       ensure
-        Process.wait
+        Process.wait pid
       end
     end
 
@@ -127,7 +127,7 @@ def test_s_open_nolock
       end
       return unless have_fork?	# snip this test
 
-      fork() {
+      pid = fork() {
         assert_instance_of(DBM, dbm  = DBM.open("tmptest_dbm", 0644,
                                                   DBM::NOLOCK))
         sleep 2
@@ -139,13 +139,13 @@ def test_s_open_nolock
           assert_instance_of(DBM, dbm2 = DBM.open("tmptest_dbm", 0644))
         }
       ensure
-        Process.wait
+        Process.wait pid
         dbm2.close if dbm2
       end
 
       p Dir.glob("tmptest_dbm*") if $DEBUG
 
-      fork() {
+      pid = fork() {
         assert_instance_of(DBM, dbm  = DBM.open("tmptest_dbm", 0644))
         sleep 2
       }
@@ -158,7 +158,7 @@ def test_s_open_nolock
                                                      DBM::NOLOCK))
         }
       ensure
-        Process.wait
+        Process.wait pid
         dbm2.close if dbm2
       end
     end
@@ -590,8 +590,32 @@ def teardown
       FileUtils.rm_rf TMPROOT if File.directory?(TMPROOT)
     end
 
+    def test_reader_open_notexist
+      assert_raise(Errno::ENOENT) {
+        DBM.open("#{TMPROOT}/a", 0666, DBM::READER)
+      }
+    end
+
+    def test_writer_open_notexist
+      assert_raise(Errno::ENOENT) {
+        DBM.open("#{TMPROOT}/a", 0666, DBM::WRITER)
+      }
+    end
+
+    def test_wrcreat_open_notexist
+      v = DBM.open("#{TMPROOT}/a", 0666, DBM::WRCREAT)
+      assert_instance_of(DBM, v)
+      v.close
+    end
+
+    def test_newdb_open_notexist
+      v = DBM.open("#{TMPROOT}/a", 0666, DBM::NEWDB)
+      assert_instance_of(DBM, v)
+      v.close
+    end
+
     def test_reader_open
-      DBM.open("#{TMPROOT}/a") {}
+      DBM.open("#{TMPROOT}/a") {} # create a db.
       v = DBM.open("#{TMPROOT}/a", nil, DBM::READER) {|d|
         # Errno::EPERM is raised on Solaris which use ndbm.
         # DBMError is raised on Debian which use gdbm. 
diff --git a/test/gdbm/test_gdbm.rb b/test/gdbm/test_gdbm.rb
index 307cd1c3da8045..db4a6564369739 100644
--- a/test/gdbm/test_gdbm.rb
+++ b/test/gdbm/test_gdbm.rb
@@ -118,7 +118,7 @@ def test_s_open_with_block
     end
     def test_s_open_lock
       return unless have_fork?	# snip this test
-      fork() {
+      pid = fork() {
         assert_instance_of(GDBM, gdbm  = GDBM.open("tmptest_gdbm", 0644))
         sleep 2
       }
@@ -132,7 +132,7 @@ def test_s_open_lock
           end
         }
       ensure
-        Process.wait
+        Process.wait pid
       end
     end
 
@@ -158,7 +158,7 @@ def test_s_open_nolock
       end
       return unless have_fork?	# snip this test
 
-      fork() {
+      pid = fork() {
         assert_instance_of(GDBM, gdbm  = GDBM.open("tmptest_gdbm", 0644,
                                                   GDBM::NOLOCK))
         sleep 2
@@ -170,13 +170,13 @@ def test_s_open_nolock
           assert_instance_of(GDBM, gdbm2 = GDBM.open("tmptest_gdbm", 0644))
         }
       ensure
-        Process.wait
+        Process.wait pid
         gdbm2.close if gdbm2
       end
 
       p Dir.glob("tmptest_gdbm*") if $DEBUG
 
-      fork() {
+      pid = fork() {
         assert_instance_of(GDBM, gdbm  = GDBM.open("tmptest_gdbm", 0644))
         sleep 2
       }
@@ -189,7 +189,7 @@ def test_s_open_nolock
                                                      GDBM::NOLOCK))
         }
       ensure
-        Process.wait
+        Process.wait pid
         gdbm2.close if gdbm2
       end
     end
@@ -660,8 +660,32 @@ def teardown
       FileUtils.rm_rf TMPROOT if File.directory?(TMPROOT)
     end
 
+    def test_reader_open_notexist
+      assert_raise(Errno::ENOENT) {
+        GDBM.open("#{TMPROOT}/a", 0666, GDBM::READER)
+      }
+    end
+
+    def test_writer_open_notexist
+      assert_raise(Errno::ENOENT) {
+        GDBM.open("#{TMPROOT}/a", 0666, GDBM::WRITER)
+      }
+    end
+
+    def test_wrcreat_open_notexist
+      v = GDBM.open("#{TMPROOT}/a", 0666, GDBM::WRCREAT)
+      assert_instance_of(GDBM, v)
+      v.close
+    end
+
+    def test_newdb_open_notexist
+      v = GDBM.open("#{TMPROOT}/a", 0666, GDBM::NEWDB)
+      assert_instance_of(GDBM, v)
+      v.close
+    end
+
     def test_reader_open
-      GDBM.open("#{TMPROOT}/a.dbm") {}
+      GDBM.open("#{TMPROOT}/a.dbm") {} # create a db.
       v = GDBM.open("#{TMPROOT}/a.dbm", nil, GDBM::READER) {|d|
         assert_raises(GDBMError) { d["k"] = "v" }
         true
diff --git a/test/sdbm/test_sdbm.rb b/test/sdbm/test_sdbm.rb
index 3cc75bf23c384d..09062d311f0ce4 100644
--- a/test/sdbm/test_sdbm.rb
+++ b/test/sdbm/test_sdbm.rb
@@ -81,7 +81,7 @@ def test_s_open_nolock
     end
     return unless have_fork?	# snip this test
 
-    fork() {
+    pid = fork() {
       assert_instance_of(SDBM, sdbm  = SDBM.open("tmptest_sdbm", 0644,
 						SDBM::NOLOCK))
       sleep 2
@@ -93,13 +93,13 @@ def test_s_open_nolock
 	assert_instance_of(SDBM, sdbm2 = SDBM.open("tmptest_sdbm", 0644))
       }
     ensure
-      Process.wait
+      Process.wait pid
       sdbm2.close if sdbm2
     end
 
     p Dir.glob("tmptest_sdbm*") if $DEBUG
 
-    fork() {
+    pid = fork() {
       assert_instance_of(SDBM, sdbm  = SDBM.open("tmptest_sdbm", 0644))
       sleep 2
     }
@@ -112,7 +112,7 @@ def test_s_open_nolock
 						   SDBM::NOLOCK))
       }
     ensure
-      Process.wait
+      Process.wait pid
       sdbm2.close if sdbm2
     end
   end