Index: test/wal5.test
==================================================================
--- test/wal5.test
+++ test/wal5.test
@@ -137,10 +137,13 @@
        [wal_page_count test.db ] \
        [db_page_count  test.db2] \
        [wal_page_count test.db2]
 }
 
+# Test that executing "PRAGMA wal_checkpoint" checkpoints all attached
+# databases, not just the main db.
+#
 do_multiclient_test tn {
   setup_and_attach_aux
   do_test 2.1.$tn.1 {
     sql1 {
       CREATE TABLE t1(a, b);
@@ -147,57 +150,110 @@
       INSERT INTO t1 VALUES(1, 2);
       CREATE TABLE aux.t2(a, b);
       INSERT INTO t2 VALUES(1, 2);
     }
   } {}
-
   do_test 2.2.$tn.2 { file_page_counts } {1 5 1 5}
   do_test 2.1.$tn.3 { sql1 { PRAGMA wal_checkpoint } } {0 5 5}
   do_test 2.1.$tn.4 { file_page_counts } {2 5 2 5}
 }
 
 do_multiclient_test tn {
-
   setup_and_attach_aux
-
   do_test 2.2.$tn.1 {
     execsql {
       CREATE TABLE t1(a, b);
       INSERT INTO t1 VALUES(1, 2);
       CREATE TABLE aux.t2(a, b);
       INSERT INTO t2 VALUES(1, 2);
       INSERT INTO t2 VALUES(3, 4);
     }
   } {}
-
   do_test 2.2.$tn.2 { file_page_counts } {1 5 1 7}
   do_test 2.2.$tn.3 { sql2 { BEGIN; SELECT * FROM t1 } } {1 2}
   do_test 2.2.$tn.4 { sql1 { PRAGMA wal_checkpoint = RESTART } } {1 5 5}
   do_test 2.2.$tn.5 { file_page_counts } {2 5 2 7}
 }
 
 do_multiclient_test tn {
-
   setup_and_attach_aux
-
   do_test 2.3.$tn.1 {
     execsql {
       CREATE TABLE t1(a, b);
       INSERT INTO t1 VALUES(1, 2);
       CREATE TABLE aux.t2(a, b);
       INSERT INTO t2 VALUES(1, 2);
     }
   } {}
-
   do_test 2.3.$tn.2 { file_page_counts } {1 5 1 5}
   do_test 2.3.$tn.3 { sql2 { BEGIN; SELECT * FROM t1 } } {1 2}
   do_test 2.3.$tn.4 { sql1 { INSERT INTO t1 VALUES(3, 4) } } {}
   do_test 2.3.$tn.5 { sql1 { INSERT INTO t2 VALUES(3, 4) } } {}
   do_test 2.3.$tn.6 { file_page_counts } {1 7 1 7}
-
   do_test 2.3.$tn.7 { sql1 { PRAGMA wal_checkpoint = FULL } } {1 7 5}
   do_test 2.3.$tn.8 { file_page_counts } {1 7 2 7}
 }
 
+# Check that checkpoints block on the correct locks. And respond correctly
+# if they cannot obtain those locks. There are three locks that a checkpoint
+# may block on (in the following order):
+#
+#   1. The writer lock: FULL and RESTART checkpoints block until any writer
+#      process releases its lock.
+#
+#   2. Readers using part of the log file. FULL and RESTART checkpoints block
+#      until readers using part (but not all) of the log file have finished.
+#
+#   3. Readers using any of the log file. After copying data into the
+#      database file, RESTART checkpoints block until readers using any part
+#      of the log file have finished.
+#
+foreach {tn1 checkpoint busy_on ckpt_expected expected} {
+  1   PASSIVE   -   {0 5 5}   -
+  2   TYPO      -   {0 5 5}   -
+
+  3   FULL      -   {0 7 7}   2
+  4   FULL      1   {1 5 5}   1
+  5   FULL      2   {1 7 5}   2
+  6   FULL      3   {0 7 7}   2
+
+  7   RESTART   -   {0 7 7}   3
+  8   RESTART   1   {1 5 5}   1
+  9   RESTART   2   {1 7 5}   2
+  10  RESTART   3   {1 7 7}   3
+
+} {
+  do_multiclient_test tn {
+    setup_and_attach_aux
+  
+    proc busyhandler {x} {
+      set ::max_busyhandler $x
+      if {$::busy_on!="-" && $x==$::busy_on} { return 1 }
+      switch -- $x {
+        1 { sql2 "COMMIT ; BEGIN ; SELECT * FROM t1" }
+        2 { sql3 "COMMIT" }
+        3 { sql2 "COMMIT" }
+      }
+      return 0
+    }
+    set ::max_busyhandler -
+  
+    do_test 2.4.$tn1.$tn.1 {
+      sql1 {
+        CREATE TABLE t1(a, b);
+        INSERT INTO t1 VALUES(1, 2);
+      }
+      sql2 { BEGIN; INSERT INTO t1 VALUES(3, 4) }
+      sql3 { BEGIN; SELECT * FROM t1 }
+    } {1 2}
+  
+    do_test 2.4.$tn1.$tn.2 {
+      code1 { db busy busyhandler }
+      sql1 "PRAGMA wal_checkpoint = $checkpoint"
+    } $ckpt_expected
+    do_test 2.4.$tn1.$tn.3 { set ::max_busyhandler } $expected
+  }
+}
 
 
 finish_test
+