Merge pull request 'postgres-integration-tests' (#89) from postgres-integration-tests into main

Reviewed-on: #89

.gitignore

@@ -12,3 +12,4 @@ pglabAll.pro.user.4.8-pre1
 *.user
 /pglabAll.pro.user*
 /public/
+/Testing/Temporary

.idea/pgLab.iml

@@ -1,2 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<module classpath="CIDR" type="CPP_MODULE" version="4" />

.junie/skills/pg-integration-tests/SKILL.md

@@ -0,0 +1,43 @@
+---
+name: pg-integration-tests
+description: Write and run pgLab tests against a real PostgreSQL server (14–17) using the pgintegration harness (DbTest fixture, template database, REQUIRE_PG_AT_LEAST). Use whenever a test needs a live server, e.g. catalog introspection, generated SQL that must be executed, version-specific behaviour, or when the user mentions integration tests, IntegrationTests, docker-compose Postgres or TEST_DATABASE_URL.
+---
+
+# Integration tests against real PostgreSQL
+
+Build/run commands live in `AGENTS.md` (Build and test); don't duplicate them here.
+
+## When to use
+Use for behaviour that depends on a real server: catalog queries, `pg_get_*` output, executing generated SQL, version differences. Pure string/logic tests belong in `PgsqlTests` / `pglabtests` instead.
+
+## Layout
+- `tests/pgintegration/` – static lib: `PgEnv` (global environment, builds template DB `tmpl_<pid>` from `fixtures/schema.sql`), `DbTest` fixture, helpers.
+- `tests/integration/` – `IntegrationTests` executable, `tst_*.cpp`, `fixtures/schema.sql`, `docker-compose.yml`.
+- The binary only reads `TEST_DATABASE_URL`; unset means every `DbTest` skips.
+
+## Writing a test
+```cpp
+#include "DbTest.h"
+#include "PgTestEnvironment.h"
+class MyFeature : public pgtest::DbTest {};
+
+TEST_F(MyFeature, Works)
+{
+    REQUIRE_PG_AT_LEAST(15);               // skip on older servers
+    auto r = conn().query("SELECT 1");     // Pgsql::Connection, throws on SQL error
+    EXPECT_EQ(r.rows(), 1);
+}
+```
+- Derive from `pgtest::DbTest`. Each test gets a fresh database (`t_<n>_<pid>`) cloned from the template and dropped afterwards, so never rely on state from another test and freely modify data/schema.
+- `conn()` is the test connection, `dbUrl()` gives a URL for code under test that opens its own connection (close those before the test ends; teardown uses `DROP DATABASE ... WITH (FORCE)`).
+- Gate version-specific features with `REQUIRE_PG_AT_LEAST(v)`; use `pgtest::serverVersionNum()` for finer checks. Also test graceful behaviour on PG 14.
+- `query()` throws on error; use `EXPECT_THROW` for expected failures.
+
+## Adding things
+- New test file: add it to the `add_executable(IntegrationTests ...)` list in `tests/integration/CMakeLists.txt` (no globbing).
+- Shared schema: extend `tests/integration/fixtures/schema.sql` (plain multi-statement SQL, loaded once per process into the template). Keep it small; it must work on all of 14–17. Version-specific schema should be created inside the test.
+- Cluster-wide objects (roles, tablespaces) are not isolated by cloning: use unique names (include `pgtest::processId()`) and drop them in `TearDown`.
+
+## Running and checking
+- One version manually: set `TEST_DATABASE_URL` and use `--gtest_filter` (see AGENTS.md); start servers with `docker compose -f tests/integration/docker-compose.yml up -d --wait pg16`, stop with `down -v`.
+- After a run no `t_*` or `tmpl_*` databases should remain: `psql <url> -Atc "select datname from pg_database where datname ~ '^(t|tmpl)_'"`.

AGENTS.md

@@ -18,6 +18,7 @@ cmake --build build
 ctest --test-dir build --output-on-failure
 ```
 - Run one suite: `./build/tests/pglabtests/pglabtests --gtest_filter='SqlLexer*'` (same for `PgsqlTests`).
+- Integration tests against real PostgreSQL 14–17 (`IntegrationTests`, label `integration`): configure with `-DPGLAB_INTEGRATION_TESTS=ON` (needs Docker), then `ctest --test-dir build -L integration -j4`. This starts `tests/integration/docker-compose.yml` (ports 54314–54317), runs the binary once per version and tears it down. Manual run against any server: `TEST_DATABASE_URL=postgresql://postgres:test@localhost:54316/postgres ./build/tests/integration/IntegrationTests --gtest_filter='Smoke*'`. Without the variable the tests skip. Developer-facing only, no reno note. See the `pg-integration-tests` skill.
 - `-DBUILD_TESTS=OFF` skips tests. `build/` is git-ignored; the first configure builds dependencies and is slow.
 - Run the app headless with `QT_QPA_PLATFORM=offscreen ./build/pglab/pglab`. It needs a PostgreSQL server for anything useful.
 

pglab/catalog/models/DatabasesTableModel.cpp

@@ -205,26 +205,9 @@ void DatabasesTableModel::StartLoadDatabaseSizes(std::map<Oid, int> oidIndex)
 
 DatabasesTableModel::DatabaseSizes DatabasesTableModel::QueryDatabaseSizes()
 {
-    std::string q =
-        "SELECT pg_database.oid, "
-        "  case when has_database_privilege(current_role, pg_database.oid, \n"
-        "    'connect') then pg_database_size(pg_database.oid) else -1 end \n"
-        "FROM pg_database";
-
     Pgsql::Connection connection;
     connection.connect(openDatabase->config().connectionString());
-    Pgsql::Result sizesResult = connection.query(q.c_str());
+    return loadDatabaseSizes(connection);
-
-    DatabaseSizes result;
-    result.reserve(sizesResult.rows());
-    for (auto& row : sizesResult)
-    {
-        DatabaseSize ds;
-        ds.oid = row.get(0);
-        ds.totalBytes = row.get(1);
-        result.push_back(ds);
-    }
-    return result;
 }
 
 void DatabasesTableModel::PopulateSizes(std::map<Oid, int> oidIndex, DatabaseSizes sizes)

pglab/catalog/models/DatabasesTableModel.h

@@ -3,6 +3,7 @@
 
 #include "BaseTableModel.h"
 #include "catalog/PgDatabase.h"
+#include "catalog/PgDatabaseSizes.h"
 #include <memory>
 
 class OpenDatabase;
@@ -45,17 +46,8 @@ public:
 protected:
     virtual QVariant getDataMeaning(const QModelIndex &index) const override;
 private:
-    class DatabaseSize {
+    using DatabaseSize = PgDatabaseSize;
-    public:
+    using DatabaseSizes = PgDatabaseSizes;
-        Oid oid;
-        int64_t totalBytes;
-
-        DatabaseSize()
-            : oid(InvalidOid)
-            , totalBytes(-1)
-        {}
-    };
-    using DatabaseSizes = std::vector<DatabaseSize>;
 
     class Database {
     public:

pglablib/CMakeLists.txt

@@ -21,6 +21,7 @@ add_library(pglablib STATIC
     catalog/PgIndexContainer.cpp
     catalog/PgConstraint.cpp
     catalog/PgConstraintContainer.cpp
+    catalog/PgDatabaseSizes.cpp
     ParamListJson.cpp
     ParamListModel.cpp
     sqlite/SQLiteConnection.cpp
@@ -95,6 +96,7 @@ add_library(pglablib STATIC
     catalog/PgIndexContainer.h
     catalog/PgConstraint.h
     catalog/PgConstraintContainer.h
+    catalog/PgDatabaseSizes.h
     ParamListJson.h
     ParamListModel.h
     sqlite/SQLiteConnection.h

pglablib/catalog/PgDatabaseSizes.cpp

@@ -0,0 +1,25 @@
+#include "PgDatabaseSizes.h"
+
+#include "Pgsql_Result.h"
+
+PgDatabaseSizes loadDatabaseSizes(Pgsql::Connection &connection)
+{
+	std::string q =
+		"SELECT pg_database.oid, "
+		"  case when has_database_privilege(current_role, pg_database.oid, \n"
+		"    'connect') then pg_database_size(pg_database.oid) else -1 end \n"
+		"FROM pg_database";
+
+	Pgsql::Result sizesResult = connection.query(q.c_str());
+
+	PgDatabaseSizes result;
+	result.reserve(sizesResult.rows());
+	for (auto& row : sizesResult)
+	{
+		PgDatabaseSize ds;
+		ds.oid = row.get(0);
+		ds.totalBytes = row.get(1);
+		result.push_back(ds);
+	}
+	return result;
+}

pglablib/catalog/PgDatabaseSizes.h

@@ -0,0 +1,25 @@
+#ifndef PGDATABASESIZES_H
+#define PGDATABASESIZES_H
+
+#include "Pgsql_Connection.h"
+#include <libpq-fe.h>
+#include <cstdint>
+#include <vector>
+
+class PgDatabaseSize {
+public:
+	Oid oid;
+	int64_t totalBytes;
+
+	PgDatabaseSize()
+		: oid(InvalidOid)
+		, totalBytes(-1)
+	{}
+};
+
+using PgDatabaseSizes = std::vector<PgDatabaseSize>;
+
+/// Returns the size of every database. The size is -1 when the current role has no CONNECT privilege.
+PgDatabaseSizes loadDatabaseSizes(Pgsql::Connection &connection);
+
+#endif // PGDATABASESIZES_H

tests/CMakeLists.txt

@@ -3,3 +3,5 @@ find_package(GTest CONFIG REQUIRED)
 add_subdirectory(mygtestutils)
 add_subdirectory(PgsqlTests)
 add_subdirectory(pglabtests)
+add_subdirectory(pgintegration)
+add_subdirectory(integration)

tests/integration/CMakeLists.txt

@@ -0,0 +1,46 @@
+add_executable(IntegrationTests
+    main.cpp
+    tst_Smoke.cpp
+    tst_CatalogLoad.cpp
+    tst_DatabaseSizes.cpp
+    )
+
+target_link_libraries(IntegrationTests PRIVATE
+    pgintegration
+    pglablib
+    GTest::gtest
+    Qt6::Core
+    )
+
+target_compile_definitions(IntegrationTests PRIVATE
+    PGTEST_FIXTURE_DIR="${CMAKE_CURRENT_SOURCE_DIR}/fixtures"
+    )
+
+set_target_properties(IntegrationTests PROPERTIES
+    CXX_STANDARD 20
+    CXX_STANDARD_REQUIRED ON
+    )
+
+option(PGLAB_INTEGRATION_TESTS "Register Docker based PostgreSQL integration tests" OFF)
+
+if (PGLAB_INTEGRATION_TESTS)
+    set(PGTEST_COMPOSE_FILE ${CMAKE_CURRENT_SOURCE_DIR}/docker-compose.yml)
+
+    add_test(NAME db_up
+        COMMAND docker compose -f ${PGTEST_COMPOSE_FILE} up -d --wait)
+    add_test(NAME db_down
+        COMMAND docker compose -f ${PGTEST_COMPOSE_FILE} down -v)
+    set_tests_properties(db_up PROPERTIES FIXTURES_SETUP pgcluster LABELS integration)
+    set_tests_properties(db_down PROPERTIES FIXTURES_CLEANUP pgcluster LABELS integration)
+
+    foreach (v 14 15 16 17 18)
+        add_test(NAME integration_pg${v} COMMAND IntegrationTests)
+        set_tests_properties(integration_pg${v} PROPERTIES
+            FIXTURES_REQUIRED pgcluster
+            LABELS integration
+            ENVIRONMENT "TEST_DATABASE_URL=postgresql://postgres:test@localhost:543${v}/postgres")
+    endforeach ()
+else ()
+    add_test(NAME IntegrationTests COMMAND IntegrationTests)
+    set_tests_properties(IntegrationTests PROPERTIES LABELS integration)
+endif ()

tests/integration/docker-compose.yml

@@ -0,0 +1,17 @@
+x-pg: &pg
+  environment: { POSTGRES_PASSWORD: test }
+  tmpfs: [/var/lib/postgresql]
+  command: >
+    postgres -c fsync=off -c synchronous_commit=off
+    -c full_page_writes=off -c max_connections=200
+  healthcheck:
+    test: ["CMD-SHELL", "pg_isready -U postgres"]
+    interval: 1s
+    retries: 30
+
+services:
+  pg14: { <<: *pg, image: "postgres:14", ports: ["54314:5432"] }
+  pg15: { <<: *pg, image: "postgres:15", ports: ["54315:5432"] }
+  pg16: { <<: *pg, image: "postgres:16", ports: ["54316:5432"] }
+  pg17: { <<: *pg, image: "postgres:17", ports: ["54317:5432"] }
+  pg18: { <<: *pg, image: "postgres:18", ports: ["54318:5432"] }

tests/integration/fixtures/schema.sql

@@ -0,0 +1,6 @@
+CREATE TABLE fixture_item (
+    id integer PRIMARY KEY,
+    name text NOT NULL
+);
+
+INSERT INTO fixture_item (id, name) VALUES (1, 'one'), (2, 'two');

tests/integration/main.cpp

@@ -0,0 +1,10 @@
+#include <gtest/gtest.h>
+
+#include "PgTestEnvironment.h"
+
+int main(int argc, char *argv[])
+{
+	::testing::InitGoogleTest(&argc, argv);
+	::testing::AddGlobalTestEnvironment(new pgtest::PgEnv(PGTEST_FIXTURE_DIR));
+	return RUN_ALL_TESTS();
+}

tests/integration/tst_CatalogLoad.cpp

@@ -0,0 +1,36 @@
+#include "DbTest.h"
+#include "PgTestEnvironment.h"
+#include "catalog/PgClassContainer.h"
+#include "catalog/PgDatabaseCatalog.h"
+#include "Pgsql_Result.h"
+
+using namespace pgtest;
+
+class CatalogLoad : public DbTest {};
+
+TEST_F(CatalogLoad, SuperuserLoadsCatalog)
+{
+	PgDatabaseCatalog catalog;
+	catalog.loadAll(conn(), {});
+
+	EXPECT_EQ(catalog.serverVersion(), serverVersionNum());
+	EXPECT_EQ(catalog.getDBName(), dbName());
+	ASSERT_NE(catalog.classes(), nullptr);
+	EXPECT_NE(catalog.classes()->getByObjectNsAndName("public", "fixture_item"), nullptr);
+}
+
+TEST_F(CatalogLoad, PlainRoleLoadsCatalog)
+{
+	auto plain = plainConn();
+	Pgsql::Result r = plain->query("SELECT rolsuper FROM pg_roles WHERE rolname = current_user");
+	ASSERT_EQ(r.rows(), 1);
+	EXPECT_EQ(QString::fromUtf8(r.val(0, 0)), QString("f"));
+
+	PgDatabaseCatalog catalog;
+	catalog.loadAll(*plain, {});
+
+	EXPECT_EQ(catalog.serverVersion(), serverVersionNum());
+	EXPECT_EQ(catalog.getDBName(), dbName());
+	ASSERT_NE(catalog.classes(), nullptr);
+	EXPECT_NE(catalog.classes()->getByObjectNsAndName("public", "fixture_item"), nullptr);
+}

tests/integration/tst_DatabaseSizes.cpp

@@ -0,0 +1,68 @@
+#include "DbTest.h"
+#include "PgTestEnvironment.h"
+#include "catalog/PgDatabaseSizes.h"
+#include "Pgsql_Result.h"
+
+using namespace pgtest;
+
+namespace {
+
+Oid oidOfDatabase(Pgsql::Connection &c, const QString &db)
+{
+	Pgsql::Result r = c.query(QString("SELECT oid FROM pg_database WHERE datname = '%1'").arg(db));
+	if (!r || r.rows() != 1)
+		return InvalidOid;
+	return QString::fromUtf8(r.val(0, 0)).toUInt();
+}
+
+const PgDatabaseSize *findSize(const PgDatabaseSizes &sizes, Oid oid)
+{
+	for (const auto &s : sizes) {
+		if (s.oid == oid)
+			return &s;
+	}
+	return nullptr;
+}
+
+} // namespace
+
+class DatabaseSizes : public DbTest {};
+
+TEST_F(DatabaseSizes, ConnectableDatabaseReturnsSize)
+{
+	auto plain = plainConn();
+	Oid oid = oidOfDatabase(*plain, dbName());
+	ASSERT_NE(oid, InvalidOid);
+
+	PgDatabaseSizes sizes = loadDatabaseSizes(*plain);
+	const PgDatabaseSize *s = findSize(sizes, oid);
+	ASSERT_NE(s, nullptr);
+	EXPECT_GE(s->totalBytes, 0);
+}
+
+TEST_F(DatabaseSizes, RevokedConnectReturnsMinusOne)
+{
+	Oid oid = oidOfDatabase(conn(), dbName());
+	ASSERT_NE(oid, InvalidOid);
+	conn().query(QString("REVOKE CONNECT ON DATABASE %1 FROM PUBLIC").arg(quoteIdent(dbName())));
+
+	auto plain = std::make_unique<Pgsql::Connection>();
+	plain->connect(urlForDbAsPlainRole("postgres"));
+
+	PgDatabaseSizes sizes = loadDatabaseSizes(*plain);
+	const PgDatabaseSize *s = findSize(sizes, oid);
+	ASSERT_NE(s, nullptr);
+	EXPECT_EQ(s->totalBytes, -1);
+}
+
+TEST_F(DatabaseSizes, SuperuserSeesAllDatabases)
+{
+	PgDatabaseSizes sizes = loadDatabaseSizes(conn());
+
+	Pgsql::Result r = conn().query("SELECT count(*) FROM pg_database");
+	ASSERT_EQ(r.rows(), 1);
+	EXPECT_EQ(static_cast<size_t>(QString::fromUtf8(r.val(0, 0)).toULongLong()), sizes.size());
+
+	for (const auto &s : sizes)
+		EXPECT_GE(s.totalBytes, 0) << "database oid " << s.oid;
+}

tests/integration/tst_Smoke.cpp

@@ -0,0 +1,63 @@
+#include "DbTest.h"
+#include "PgTestEnvironment.h"
+#include "Pgsql_Result.h"
+
+using namespace pgtest;
+
+namespace {
+
+int scalarInt(Pgsql::Connection &c, const char *sql)
+{
+	Pgsql::Result r = c.query(sql);
+	EXPECT_EQ(r.rows(), 1);
+	return QString::fromUtf8(r.val(0, 0)).toInt();
+}
+
+} // namespace
+
+class Smoke : public DbTest {};
+
+TEST_F(Smoke, SelectOne)
+{
+	EXPECT_EQ(scalarInt(conn(), "SELECT 1"), 1);
+}
+
+TEST_F(Smoke, RunsOnClonedDatabase)
+{
+	Pgsql::Result r = conn().query("SELECT current_database()");
+	ASSERT_EQ(r.rows(), 1);
+	EXPECT_EQ(QString::fromUtf8(r.val(0, 0)), dbName());
+	EXPECT_TRUE(dbName().startsWith("t_"));
+}
+
+TEST_F(Smoke, ServerVersionAtLeast14)
+{
+	EXPECT_GE(serverVersionNum(), 140000);
+}
+
+TEST_F(Smoke, FixtureSchemaPresent)
+{
+	EXPECT_EQ(scalarInt(conn(), "SELECT count(*) FROM fixture_item"), 2);
+}
+
+// The two tests below each modify the database and expect the pristine
+// fixture state, in whichever order they run.
+TEST_F(Smoke, IsolationA)
+{
+	EXPECT_EQ(scalarInt(conn(), "SELECT count(*) FROM fixture_item"), 2);
+	conn().query("INSERT INTO fixture_item VALUES (100, 'a')");
+	EXPECT_EQ(scalarInt(conn(), "SELECT count(*) FROM fixture_item"), 3);
+}
+
+TEST_F(Smoke, IsolationB)
+{
+	EXPECT_EQ(scalarInt(conn(), "SELECT count(*) FROM fixture_item"), 2);
+	conn().query("DELETE FROM fixture_item");
+	EXPECT_EQ(scalarInt(conn(), "SELECT count(*) FROM fixture_item"), 0);
+}
+
+TEST_F(Smoke, VersionGate)
+{
+	REQUIRE_PG_AT_LEAST(15);
+	EXPECT_GE(serverVersionNum(), 150000);
+}

tests/pgintegration/CMakeLists.txt

@@ -0,0 +1,21 @@
+add_library(pgintegration STATIC
+    PgTestEnvironment.h
+    PgTestEnvironment.cpp
+    DbTest.h
+    DbTest.cpp
+    )
+
+target_link_libraries(pgintegration PUBLIC
+    pgsql
+    GTest::gtest
+    Qt6::Core
+    )
+
+target_include_directories(pgintegration PUBLIC
+    ${CMAKE_CURRENT_SOURCE_DIR}
+    )
+
+set_target_properties(pgintegration PROPERTIES
+    CXX_STANDARD 20
+    CXX_STANDARD_REQUIRED ON
+    )

tests/pgintegration/DbTest.cpp

@@ -0,0 +1,62 @@
+#include "DbTest.h"
+#include "PgTestEnvironment.h"
+
+#include <atomic>
+#include <stdexcept>
+
+namespace pgtest {
+
+namespace {
+std::atomic<int> g_counter{0};
+}
+
+QString DbTest::dbUrl() const
+{
+    return urlForDb(dbName_);
+}
+
+std::unique_ptr<Pgsql::Connection> DbTest::plainConn() const
+{
+    auto c = std::make_unique<Pgsql::Connection>();
+    c->connect(urlForDbAsPlainRole(dbName_));
+    return c;
+}
+
+void DbTest::SetUp()
+{
+    if (!available())
+        GTEST_SKIP() << "TEST_DATABASE_URL not set or template database unavailable";
+
+    dbName_ = QString("t_%1_%2").arg(g_counter++).arg(processId());
+    try {
+        {
+            Pgsql::Connection admin;
+            admin.connect(*baseUrl());
+            admin.query(QString("CREATE DATABASE %1 TEMPLATE %2")
+                        .arg(quoteIdent(dbName_), quoteIdent(templateDbName())));
+        }
+        conn_ = std::make_unique<Pgsql::Connection>();
+        conn_->connect(dbUrl());
+    }
+    catch (const std::exception &e) {
+        FAIL() << "Creating test database failed: " << e.what();
+    }
+}
+
+void DbTest::TearDown()
+{
+    conn_.reset();
+    if (dbName_.isEmpty())
+        return;
+    try {
+        Pgsql::Connection admin;
+        admin.connect(*baseUrl());
+        admin.query(QString("DROP DATABASE IF EXISTS %1 WITH (FORCE)").arg(quoteIdent(dbName_)));
+    }
+    catch (const std::exception &e) {
+        ADD_FAILURE() << "Dropping test database failed: " << e.what();
+    }
+    dbName_.clear();
+}
+
+} // namespace pgtest

tests/pgintegration/DbTest.h

@@ -0,0 +1,28 @@
+#pragma once
+
+#include <gtest/gtest.h>
+#include <memory>
+#include <QString>
+
+#include "Pgsql_Connection.h"
+
+namespace pgtest {
+
+/// Fixture giving every test its own database cloned from the template.
+class DbTest : public ::testing::Test {
+protected:
+    void SetUp() override;
+    void TearDown() override;
+
+    Pgsql::Connection& conn() { return *conn_; }
+    QString dbName() const { return dbName_; }
+    QString dbUrl() const;
+    /// Opens a new connection to this test's database as the plain (non-superuser) role.
+    std::unique_ptr<Pgsql::Connection> plainConn() const;
+
+private:
+    QString dbName_;
+    std::unique_ptr<Pgsql::Connection> conn_;
+};
+
+} // namespace pgtest

tests/pgintegration/PgTestEnvironment.cpp

@@ -0,0 +1,149 @@
+#include "PgTestEnvironment.h"
+
+#include <QCoreApplication>
+#include <QFile>
+#include <QUrl>
+#include <iostream>
+#include <stdexcept>
+
+#include "Pgsql_Connection.h"
+#include "Pgsql_Result.h"
+
+namespace pgtest {
+
+namespace {
+
+bool g_available = false;
+int g_versionNum = 0;
+
+const char *kPlainRolePassword = "pglab_plain_test";
+
+} // namespace
+
+std::optional<QString> baseUrl()
+{
+    QByteArray v = qgetenv("TEST_DATABASE_URL");
+    if (v.isEmpty())
+        return std::nullopt;
+    return QString::fromUtf8(v);
+}
+
+QString urlForDb(const QString &db)
+{
+    auto base = baseUrl();
+    if (!base)
+        throw std::runtime_error("TEST_DATABASE_URL is not set");
+    QUrl url(*base);
+    url.setPath("/" + db);
+    return url.toString();
+}
+
+bool available()
+{
+    return g_available;
+}
+
+int serverVersionNum()
+{
+    return g_versionNum;
+}
+
+qint64 processId()
+{
+    return QCoreApplication::applicationPid();
+}
+
+QString templateDbName()
+{
+    return QString("tmpl_%1").arg(processId());
+}
+
+QString plainRoleName()
+{
+    return QString("tst_%1").arg(processId());
+}
+
+QString urlForDbAsPlainRole(const QString &db)
+{
+    auto base = baseUrl();
+    if (!base)
+        throw std::runtime_error("TEST_DATABASE_URL is not set");
+    QUrl url(*base);
+    url.setPath("/" + db);
+    url.setUserName(plainRoleName());
+    url.setPassword(QString::fromUtf8(kPlainRolePassword));
+    return url.toString();
+}
+
+QString quoteIdent(const QString &name)
+{
+    QString r = name;
+    r.replace('"', "\"\"");
+    return "\"" + r + "\"";
+}
+
+void PgEnv::SetUp()
+{
+    auto base = baseUrl();
+    if (!base) {
+        std::cerr << "TEST_DATABASE_URL not set, integration tests will be skipped\n";
+        return;
+    }
+
+    const QString tmpl = templateDbName();
+    try {
+        {
+            Pgsql::Connection admin;
+            admin.connect(*base);
+            Pgsql::Result r = admin.query("SHOW server_version_num");
+            if (!r || r.rows() != 1)
+                throw std::runtime_error("could not query server_version_num");
+            g_versionNum = QString::fromUtf8(r.val(0, 0)).toInt();
+            admin.query(QString("DROP DATABASE IF EXISTS %1 WITH (FORCE)").arg(quoteIdent(tmpl)));
+            admin.query(QString("CREATE DATABASE %1").arg(quoteIdent(tmpl)));
+            admin.query(QString("DROP ROLE IF EXISTS %1").arg(quoteIdent(plainRoleName())));
+            admin.query(QString("CREATE ROLE %1 LOGIN NOSUPERUSER NOCREATEDB NOCREATEROLE PASSWORD '%2'")
+                        .arg(quoteIdent(plainRoleName()), QString::fromUtf8(kPlainRolePassword)));
+        }
+        {
+            QFile f(fixtureDir_ + "/schema.sql");
+            if (!f.open(QIODevice::ReadOnly))
+                throw std::runtime_error("cannot open " + f.fileName().toStdString());
+            QByteArray sql = f.readAll();
+
+            Pgsql::Connection c;
+            c.connect(urlForDb(tmpl));
+            c.query(sql.constData());
+        }
+        g_available = true;
+    }
+    catch (const std::exception &e) {
+        ADD_FAILURE() << "Setting up template database failed: " << e.what();
+        try {
+            Pgsql::Connection admin;
+            admin.connect(*base);
+            admin.query(QString("DROP DATABASE IF EXISTS %1 WITH (FORCE)").arg(quoteIdent(tmpl)));
+            admin.query(QString("DROP ROLE IF EXISTS %1").arg(quoteIdent(plainRoleName())));
+        }
+        catch (const std::exception &) {
+        }
+    }
+}
+
+void PgEnv::TearDown()
+{
+    if (!g_available)
+        return;
+    try {
+        Pgsql::Connection admin;
+        admin.connect(*baseUrl());
+        admin.query(QString("DROP DATABASE IF EXISTS %1 WITH (FORCE)").arg(quoteIdent(templateDbName())));
+        admin.query(QString("DROP ROLE IF EXISTS %1").arg(quoteIdent(plainRoleName())));
+    }
+    catch (const std::exception &e) {
+        ADD_FAILURE() << "Dropping template database or plain role failed: " << e.what();
+    }
+    g_available = false;
+}
+
+} // namespace pgtest

tests/pgintegration/PgTestEnvironment.h

@@ -0,0 +1,52 @@
+#pragma once
+
+#include <gtest/gtest.h>
+#include <optional>
+#include <QString>
+
+namespace pgtest {
+
+/// Value of the TEST_DATABASE_URL environment variable, if set and non-empty.
+std::optional<QString> baseUrl();
+
+/// Same as baseUrl() but with the database name replaced.
+QString urlForDb(const QString &db);
+
+/// True when a server is configured and the template database was created.
+bool available();
+
+/// server_version_num of the server under test (0 when unavailable).
+int serverVersionNum();
+
+/// Portable process id.
+qint64 processId();
+
+/// Name of the template database for this process.
+QString templateDbName();
+
+/// Name of the login role without superuser rights, unique per process.
+QString plainRoleName();
+
+/// Same as urlForDb() but with the plain role as user.
+QString urlForDbAsPlainRole(const QString &db);
+
+/// Quotes an identifier for use in SQL.
+QString quoteIdent(const QString &name);
+
+/// Global environment, register it in main():
+///   ::testing::AddGlobalTestEnvironment(new pgtest::PgEnv(PGTEST_FIXTURE_DIR));
+/// Creates a template database from <fixtureDir>/schema.sql once per process.
+class PgEnv : public ::testing::Environment {
+public:
+    explicit PgEnv(QString fixtureDir) : fixtureDir_(std::move(fixtureDir)) {}
+    void SetUp() override;
+    void TearDown() override;
+
+private:
+    QString fixtureDir_;
+};
+
+} // namespace pgtest
+
+#define REQUIRE_PG_AT_LEAST(v) \
+    if (pgtest::serverVersionNum() < (v) * 10000) GTEST_SKIP() << "needs PG " #v