Fixed exists_table and bumped to 0.1.11.0

Changelog.markdown

@@ -1,5 +1,9 @@
 # Changelog
 
+## 0.1.11.0
+* Improved documentation
+* Fixed exists_table
+
 ## 0.1.10.1
 * Fixed hackage warnings
 

postgresql-simple-migration.cabal

@@ -1,5 +1,5 @@
 name:                       postgresql-simple-migration
-version:                    0.1.10.1
+version:                    0.1.11.0
 synopsis:                   PostgreSQL Schema Migrations
 homepage:                   https://github.com/ameingast/postgresql-simple-migration
 Bug-reports:                https://github.com/ameingast/postgresql-simple-migration/issues

src/Database/PostgreSQL/Simple/Migration.hs

@@ -47,8 +47,8 @@ import qualified Crypto.Hash.MD5                    as MD5 (hash)
 import qualified Data.ByteString                    as BS (ByteString, readFile)
 import qualified Data.ByteString.Base64             as B64 (encode)
 import           Data.Foldable                      (Foldable)
-import           Data.Traversable                   (Traversable)
 import           Data.List                          (isPrefixOf, sort)
+import           Data.Traversable                   (Traversable)
 #if __GLASGOW_HASKELL__ < 710
 import           Data.Monoid                        (Monoid (..))
 #endif

src/Database/PostgreSQL/Simple/Util.hs

@@ -25,10 +25,14 @@ import           Database.PostgreSQL.Simple (Connection, Only (..), begin,
 -- | Checks if the table with the given name exists in the database.
 existsTable :: Connection -> String -> IO Bool
 existsTable con table =
-    fmap (not . null) (query con q (Only table) :: IO [[Int]])
+    fmap checkRowCount (query con q (Only table) :: IO [[Int]])
     where
         q = "select count(relname) from pg_class where relname = ?"
 
+        checkRowCount :: [[Int]] -> Bool
+        checkRowCount ((1:_):_) = True
+        checkRowCount _         = False
+
 -- | Executes the given IO monad inside a transaction and performs a roll-back
 -- afterwards (even if exceptions occur).
 withTransactionRolledBack :: Connection -> IO a -> IO a

test/Database/PostgreSQL/Simple/MigrationTest.hs

@@ -33,12 +33,21 @@ migrationSpec con = describe "Migrations" $ do
     let migrationDir = MigrationDirectory "share/test/scripts"
     let migrationFile = MigrationFile "s.sql" "share/test/script.sql"
 
+    it "asserts that the schema_migrations table does not exist" $ do
+        r <- existsTable con "schema_migrations"
+        r `shouldBe` False
+
+    it "validates an initialization on an empty database" $ do
+        r <- runMigration $ MigrationContext
+            (MigrationValidation MigrationInitialization) False con
+        r `shouldBe` MigrationError "No such table: schema_migrations"
+
     it "initializes a database" $ do
         r <- runMigration $ MigrationContext MigrationInitialization False con
         r `shouldBe` MigrationSuccess
 
     it "creates the schema_migrations table" $ do
-        r <- existsTable con "schema_migration"
+        r <- existsTable con "schema_migrations"
         r `shouldBe` True
 
     it "executes a migration script" $ do