Simplify discard tests

test/test_discarding.rb

@@ -2,30 +2,54 @@
 
 module SQLite3
   class TestDiscardDatabase < SQLite3::TestCase
+    DBPATH = "test.db"
+
+    def setup
+      FileUtils.rm_f(DBPATH)
+      super
+    end
+
+    def teardown
+      super
+      FileUtils.rm_f(DBPATH)
+    end
+
+    def in_a_forked_process
+      @read, @write = IO.pipe
+      old_stderr, $stderr = $stderr, StringIO.new
+
+      Process.fork do
+        @read.close
+        begin
+          yield @write
+        rescue => e
+          old_stderr.write("child exception: #{e.message}")
+        end
+        @write.write($stderr.string)
+        @write.close
+        exit!
+      end
+
+      $stderr = old_stderr
+      @write.close
+      *@results = *@read.readlines
+      @read.close
+    end
+
     def test_fork_discards_an_open_readwrite_connection
       skip("interpreter doesn't support fork") unless Process.respond_to?(:fork)
       skip("valgrind doesn't handle forking") if i_am_running_in_valgrind
       skip("ruby 3.0 doesn't have Process._fork") if RUBY_VERSION < "3.1.0"
 
       GC.start
       begin
-        db = SQLite3::Database.new("test.db")
-        read, write = IO.pipe
-
-        old_stderr, $stderr = $stderr, StringIO.new
-        Process.fork do
-          read.close
+        db = SQLite3::Database.new(DBPATH)
 
+        in_a_forked_process do |write|
           write.write(db.closed? ? "ok\n" : "fail\n")
-          write.write($stderr.string)
-
-          write.close
-          exit!
         end
-        $stderr = old_stderr
-        write.close
-        assertion, *stderr = *read.readlines
-        read.close
+
+        assertion, *stderr = *@results
 
         assert_equal("ok", assertion.chomp, "closed? did not return true")
         assert_equal(1, stderr.count, "unexpected output on stderr: #{stderr.inspect}")
@@ -35,8 +59,7 @@ def test_fork_discards_an_open_readwrite_connection
           "expected warning was not emitted"
         )
       ensure
-        db.close
-        FileUtils.rm_f("test.db")
+        db&.close
       end
     end
 
@@ -46,29 +69,22 @@ def test_fork_does_not_discard_closed_connections
 
       GC.start
       begin
-        db = SQLite3::Database.new("test.db")
-        read, write = IO.pipe
-
+        db = SQLite3::Database.new(DBPATH)
         db.close
 
-        old_stderr, $stderr = $stderr, StringIO.new
-        Process.fork do
-          read.close
-
-          write.write($stderr.string)
-
-          write.close
-          exit!
+        in_a_forked_process do |write|
+          write.write(db.closed? ? "ok\n" : "fail\n")
+          write.write($stderr.string) # should be empty write, no warnings emitted
+          write.write("done\n")
         end
-        $stderr = old_stderr
-        write.close
-        stderr = read.readlines
-        read.close
 
-        assert_equal(0, stderr.count, "unexpected output on stderr: #{stderr.inspect}")
+        assertion, *rest = *@results
+
+        assert_equal("ok", assertion.chomp, "closed? did not return true")
+        assert_equal(1, rest.count, "unexpected output on stderr: #{rest.inspect}")
+        assert_equal("done", rest.first.chomp, "unexpected output on stderr: #{rest.inspect}")
       ensure
-        db.close
-        FileUtils.rm_f("test.db")
+        db&.close
       end
     end
 
@@ -78,36 +94,28 @@ def test_fork_does_not_discard_readonly_connections
 
       GC.start
       begin
-        SQLite3::Database.open("test.db") do |db|
+        SQLite3::Database.open(DBPATH) do |db|
           db.execute("create table foo (bar int)")
           db.execute("insert into foo values (1)")
         end
 
-        db = SQLite3::Database.new("test.db", readonly: true)
-        read, write = IO.pipe
-
-        old_stderr, $stderr = $stderr, StringIO.new
-        Process.fork do
-          read.close
+        db = SQLite3::Database.new(DBPATH, readonly: true)
 
+        in_a_forked_process do |write|
           write.write(db.closed? ? "fail\n" : "ok\n") # should be open and readable
           write.write((db.execute("select * from foo") == [[1]]) ? "ok\n" : "fail\n")
-          write.write($stderr.string)
-
-          write.close
-          exit!
+          write.write($stderr.string) # should be an empty write, no warnings emitted
+          write.write("done\n")
         end
-        $stderr = old_stderr
-        write.close
-        assertion1, assertion2, *stderr = *read.readlines
-        read.close
+
+        assertion1, assertion2, *rest = *@results
 
         assert_equal("ok", assertion1.chomp, "closed? did not return false")
         assert_equal("ok", assertion2.chomp, "could not read from database")
-        assert_equal(0, stderr.count, "unexpected output on stderr: #{stderr.inspect}")
+        assert_equal(1, rest.count, "unexpected output on stderr: #{rest.inspect}")
+        assert_equal("done", rest.first.chomp, "unexpected output on stderr: #{rest.inspect}")
       ensure
         db&.close
-        FileUtils.rm_f("test.db")
       end
     end
 
@@ -117,42 +125,35 @@ def test_close_does_not_discard_readonly_connections
 
       GC.start
       begin
-        SQLite3::Database.open("test.db") do |db|
+        SQLite3::Database.open(DBPATH) do |db|
           db.execute("create table foo (bar int)")
           db.execute("insert into foo values (1)")
         end
 
-        db = SQLite3::Database.new("test.db", readonly: true)
-        read, write = IO.pipe
-
-        old_stderr, $stderr = $stderr, StringIO.new
-        Process.fork do
-          read.close
+        db = SQLite3::Database.new(DBPATH, readonly: true)
 
+        in_a_forked_process do |write|
+          write.write(db.closed? ? "fail\n" : "ok\n") # should be open and readable
           db.close
-
-          write.write($stderr.string)
-
-          write.close
-          exit!
+          write.write($stderr.string) # should be an empty write, no warnings emitted
+          write.write("done\n")
         end
-        $stderr = old_stderr
-        write.close
-        stderr = read.readlines
-        read.close
 
-        assert_equal(0, stderr.count, "unexpected output on stderr: #{stderr.inspect}")
+        assertion, *rest = *@results
+
+        assert_equal("ok", assertion.chomp, "closed? did not return false")
+        assert_equal(1, rest.count, "unexpected output on stderr: #{rest.inspect}")
+        assert_equal("done", rest.first.chomp, "unexpected output on stderr: #{rest.inspect}")
       ensure
         db&.close
-        FileUtils.rm_f("test.db")
       end
     end
 
     def test_a_discarded_connection_with_statements
       skip("discard leaks memory") if i_am_running_in_valgrind
 
       begin
-        db = SQLite3::Database.new("test.db")
+        db = SQLite3::Database.new(DBPATH)
         db.execute("create table foo (bar int)")
         db.execute("insert into foo values (1)")
         stmt = db.prepare("select * from foo")
@@ -165,8 +166,7 @@ def test_a_discarded_connection_with_statements
         assert_nothing_raised { stmt.close }
         assert_predicate(stmt, :closed?)
       ensure
-        db.close
-        FileUtils.rm_f("test.db")
+        db&.close
       end
     end
   end