sql: Make Database::DoesSchemaItemExist() case-sensitive.

The method and its derivatives are supposed to be used in tests, so it's
good to be exact.

Change-Id: Ifc4d6c278a32a125e79c2f1bc6cb3defd01494ae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1558158
Reviewed-by: Chris Mumford <cmumford@google.com>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#649633}

sql/database.cc

@@ -1286,14 +1286,14 @@ bool Database::DoesViewExist(const char* view_name) const {
 }
 
 bool Database::DoesSchemaItemExist(const char* name, const char* type) const {
-  const char* kSql =
-      "SELECT name FROM sqlite_master WHERE type=? AND name=? COLLATE NOCASE";
+  static const char kSql[] =
+      "SELECT 1 FROM sqlite_master WHERE type=? AND name=?";
   Statement statement(GetUntrackedStatement(kSql));
 
-  // This can happen if the database is corrupt and the error is a test
-  // expectation.
-  if (!statement.is_valid())
+  if (!statement.is_valid()) {
+    // The database is corrupt.
     return false;
+  }
 
   statement.BindString(0, type);
   statement.BindString(1, name);

sql/database_unittest.cc

@@ -210,6 +210,10 @@ TEST_F(SQLDatabaseTest, DoesTableExist) {
   ASSERT_TRUE(db().Execute("CREATE INDEX foo_index ON foo (a)"));
   EXPECT_TRUE(db().DoesTableExist("foo"));
   EXPECT_FALSE(db().DoesTableExist("foo_index"));
+
+  // DoesTableExist() is case-sensitive.
+  EXPECT_FALSE(db().DoesTableExist("Foo"));
+  EXPECT_FALSE(db().DoesTableExist("FOO"));
 }
 
 TEST_F(SQLDatabaseTest, DoesIndexExist) {
@@ -220,6 +224,11 @@ TEST_F(SQLDatabaseTest, DoesIndexExist) {
   ASSERT_TRUE(db().Execute("CREATE INDEX foo_index ON foo (a)"));
   EXPECT_TRUE(db().DoesIndexExist("foo_index"));
   EXPECT_FALSE(db().DoesIndexExist("foo"));
+
+  // DoesIndexExist() is case-sensitive.
+  EXPECT_FALSE(db().DoesIndexExist("Foo_index"));
+  EXPECT_FALSE(db().DoesIndexExist("Foo_Index"));
+  EXPECT_FALSE(db().DoesIndexExist("FOO_INDEX"));
 }
 
 TEST_F(SQLDatabaseTest, DoesViewExist) {
@@ -228,6 +237,10 @@ TEST_F(SQLDatabaseTest, DoesViewExist) {
   EXPECT_FALSE(db().DoesIndexExist("voo"));
   EXPECT_FALSE(db().DoesTableExist("voo"));
   EXPECT_TRUE(db().DoesViewExist("voo"));
+
+  // DoesTableExist() is case-sensitive.
+  EXPECT_FALSE(db().DoesViewExist("Voo"));
+  EXPECT_FALSE(db().DoesViewExist("VOO"));
 }
 
 TEST_F(SQLDatabaseTest, DoesColumnExist) {
@@ -239,9 +252,10 @@ TEST_F(SQLDatabaseTest, DoesColumnExist) {
   ASSERT_FALSE(db().DoesTableExist("bar"));
   EXPECT_FALSE(db().DoesColumnExist("bar", "b"));
 
-  // Names are not case sensitive.
-  EXPECT_TRUE(db().DoesTableExist("FOO"));
+  // SQLite resolves table/column names without case sensitivity.
   EXPECT_TRUE(db().DoesColumnExist("FOO", "A"));
+  EXPECT_TRUE(db().DoesColumnExist("FOO", "a"));
+  EXPECT_TRUE(db().DoesColumnExist("foo", "A"));
 }
 
 TEST_F(SQLDatabaseTest, GetLastInsertRowId) {