SERVER-51617 Add test expression for API version testing

8 files changed, 312 insertions, 0 deletions

diff --git a/src/mongo/db/pipeline/SConscript b/src/mongo/db/pipeline/SConscript
index 41c30aecb02..9a5adb2ce1f 100644
--- a/src/mongo/db/pipeline/SConscript
+++ b/src/mongo/db/pipeline/SConscript
@@ -70,12 +70,14 @@ env.Library(
         'expression_context.cpp',
         'expression_function.cpp',
         'expression_js_emit.cpp',
+        'expression_test_api_version.cpp',
         'expression_trigonometric.cpp',
         'javascript_execution.cpp',
         'make_js_function.cpp',
         'variables.cpp',
     ],
     LIBDEPS=[
+        '$BUILD_DIR/mongo/db/commands/test_commands_enabled',
         '$BUILD_DIR/mongo/db/exec/document_value/document_value',
         '$BUILD_DIR/mongo/db/query/collation/collator_factory_interface',
         '$BUILD_DIR/mongo/db/query/datetime/date_time_support',
@@ -389,6 +391,7 @@ env.CppUnitTest(
         'expression_or_test.cpp',
         'expression_replace_test.cpp',
         'expression_test.cpp',
+        'expression_test_api_version_test.cpp',
         'expression_trigonometric_test.cpp',
         'expression_trim_test.cpp',
         'expression_walker_test.cpp',
diff --git a/src/mongo/db/pipeline/expression.h b/src/mongo/db/pipeline/expression.h
index cbcf74dd618..647f7a24527 100644
--- a/src/mongo/db/pipeline/expression.h
+++ b/src/mongo/db/pipeline/expression.h
@@ -41,6 +41,7 @@
 #include <vector>
 
 #include "mongo/base/init.h"
+#include "mongo/db/commands/test_commands_enabled.h"
 #include "mongo/db/exec/document_value/document.h"
 #include "mongo/db/exec/document_value/value.h"
 #include "mongo/db/pipeline/dependencies.h"
@@ -91,6 +92,20 @@ class DocumentSource;
         return Status::OK();                                                               \
     }
 
+/**
+ * Registers a Parser only if test commands are enabled. Use this if your expression is only used
+ * for testing purposes.
+ */
+#define REGISTER_TEST_EXPRESSION(key, parser)                                                  \
+    MONGO_INITIALIZER_GENERAL(                                                                 \
+        addToExpressionParserMap_##key, ("EndStartupOptionHandling"), ("expressionParserMap")) \
+    (InitializerContext*) {                                                                    \
+        if (getTestCommandsEnabled()) {                                                        \
+            Expression::registerExpression("$" #key, (parser), boost::none);                   \
+        }                                                                                      \
+        return Status::OK();                                                                   \
+    }
+
 class Expression : public RefCountable {
 public:
     using Parser = std::function<boost::intrusive_ptr<Expression>(
diff --git a/src/mongo/db/pipeline/expression_context.cpp b/src/mongo/db/pipeline/expression_context.cpp
index a27d8ca64b1..0ca09f7a27c 100644
--- a/src/mongo/db/pipeline/expression_context.cpp
+++ b/src/mongo/db/pipeline/expression_context.cpp
@@ -125,6 +125,8 @@ ExpressionContext::ExpressionContext(
     }
     if (letParameters)
         variables.seedVariablesWithLetParameters(this, *letParameters);
+    if (opCtx)
+        apiParameters = APIParameters::get(opCtx);
 }
 
 ExpressionContext::ExpressionContext(
diff --git a/src/mongo/db/pipeline/expression_context.h b/src/mongo/db/pipeline/expression_context.h
index c6a20a28ab9..721cf6ffe01 100644
--- a/src/mongo/db/pipeline/expression_context.h
+++ b/src/mongo/db/pipeline/expression_context.h
@@ -37,6 +37,7 @@
 
 #include "mongo/base/string_data.h"
 #include "mongo/bson/bsonobj.h"
+#include "mongo/db/api_parameters.h"
 #include "mongo/db/exec/document_value/document_comparator.h"
 #include "mongo/db/exec/document_value/value_comparator.h"
 #include "mongo/db/namespace_string.h"
@@ -363,6 +364,11 @@ public:
     // construction.
     const bool mayDbProfile = true;
 
+    // API Parameters pulled from OperationContext upon object creation.
+    // This may become stale if OperationContext changes after object creation.
+    // Expressions should reach APIParameters with this variable instead of using the decorator.
+    APIParameters apiParameters;
+
 protected:
     static const int kInterruptCheckPeriod = 128;
 
diff --git a/src/mongo/db/pipeline/expression_test_api_version.cpp b/src/mongo/db/pipeline/expression_test_api_version.cpp
new file mode 100644
index 00000000000..c501d8b9292
--- /dev/null
+++ b/src/mongo/db/pipeline/expression_test_api_version.cpp
@@ -0,0 +1,97 @@
+/**
+ *    Copyright (C) 2020-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/api_parameters.h"
+#include "mongo/db/pipeline/expression_test_api_version.h"
+
+namespace mongo {
+
+REGISTER_TEST_EXPRESSION(_testApiVersion, ExpressionTestApiVersion::parse);
+
+ExpressionTestApiVersion::ExpressionTestApiVersion(ExpressionContext* const expCtx,
+                                                   bool unstable,
+                                                   bool deprecated)
+    : Expression(expCtx), _unstable(unstable), _deprecated(deprecated) {}
+
+boost::intrusive_ptr<Expression> ExpressionTestApiVersion::parse(ExpressionContext* const expCtx,
+                                                                 BSONElement expr,
+                                                                 const VariablesParseState& vps) {
+    uassert(5161700,
+            "$_testApiVersion only supports an object as its argument",
+            expr.type() == BSONType::Object);
+
+    const BSONObj params = expr.embeddedObject();
+    uassert(5161701,
+            "$_testApiVersion only accepts an object with a single field.",
+            params.nFields() == 1);
+
+    bool unstableField = false;
+    bool deprecatedField = false;
+
+    auto field = params.firstElementFieldNameStringData();
+    if (field == kUnstableField) {
+        uassert(5161702, "unstable must be a boolean", params.firstElement().isBoolean());
+        unstableField = params.firstElement().boolean();
+    } else if (field == kDeprecatedField) {
+        uassert(5161703, "deprecated must be a boolean", params.firstElement().isBoolean());
+        deprecatedField = params.firstElement().boolean();
+    } else {
+        uasserted(5161704,
+                  str::stream() << field << " is not a valid argument for $_testApiVersion");
+    }
+
+    return new ExpressionTestApiVersion(expCtx, unstableField, deprecatedField);
+}
+
+Value ExpressionTestApiVersion::serialize(bool explain) const {
+    return Value(Document{{"$_testApiVersion",
+                           Document{{"unstable", _unstable ? Value(_unstable) : Value()},
+                                    {"deprecated", _deprecated ? Value(_deprecated) : Value()}}}});
+}
+
+Value ExpressionTestApiVersion::evaluate(const Document& root, Variables* variables) const {
+    APIParameters apiParams = getExpressionContext()->apiParameters;
+
+    if (apiParams.getAPIStrict() && _unstable) {
+        uasserted(ErrorCodes::APIStrictError,
+                  "Provided apiStrict is true with an unstable command.");
+    }
+
+    if (apiParams.getAPIDeprecationErrors() && _deprecated) {
+        uasserted(ErrorCodes::APIDeprecationError,
+                  "Provided apiDeprecatedErrors is true with a deprecated command.");
+    }
+
+    return Value(1);
+}
+
+void ExpressionTestApiVersion::_doAddDependencies(DepsTracker* deps) const {}
+
+}  // namespace mongo
\ No newline at end of file
diff --git a/src/mongo/db/pipeline/expression_test_api_version.h b/src/mongo/db/pipeline/expression_test_api_version.h
new file mode 100644
index 00000000000..ede9a8378d4
--- /dev/null
+++ b/src/mongo/db/pipeline/expression_test_api_version.h
@@ -0,0 +1,64 @@
+/**
+ *    Copyright (C) 2020-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+#include "mongo/db/pipeline/expression.h"
+
+namespace mongo {
+/**
+ * This expression will be used to validate that versioning code is working as expected.
+ * $_testApiVersion should only take one parameter, either {unstable: true} or {deprecated: true}.
+ * If no error is thrown, this expression will return an integer value.
+ */
+class ExpressionTestApiVersion final : public Expression {
+public:
+    static constexpr auto kUnstableField = "unstable";
+    static constexpr auto kDeprecatedField = "deprecated";
+
+    static boost::intrusive_ptr<Expression> parse(ExpressionContext* const expCtx,
+                                                  BSONElement expr,
+                                                  const VariablesParseState& vps);
+
+    Value evaluate(const Document& root, Variables* variables) const final;
+
+    Value serialize(bool explain) const final;
+
+    void acceptVisitor(ExpressionVisitor* visitor) final {
+        return visitor->visit(this);
+    }
+
+private:
+    ExpressionTestApiVersion(ExpressionContext* const expCtx, bool unstable, bool deprecated);
+    void _doAddDependencies(DepsTracker* deps) const final override;
+
+    bool _unstable;
+    bool _deprecated;
+};
+}  // namespace mongo
diff --git a/src/mongo/db/pipeline/expression_test_api_version_test.cpp b/src/mongo/db/pipeline/expression_test_api_version_test.cpp
new file mode 100644
index 00000000000..5dc4b93493e
--- /dev/null
+++ b/src/mongo/db/pipeline/expression_test_api_version_test.cpp
@@ -0,0 +1,123 @@
+/**
+ *    Copyright (C) 2020-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/db/exec/document_value/document_value_test_util.h"
+#include "mongo/db/pipeline/aggregation_context_fixture.h"
+#include "mongo/db/pipeline/expression_context_for_test.h"
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/pipeline/expression_test_api_version.h"
+#include "mongo/unittest/unittest.h"
+
+namespace mongo {
+namespace {
+
+using TestApiVersion = AggregationContextFixture;
+
+TEST_F(TestApiVersion, UnstableAcceptsBooleanValue) {
+    auto expCtx = getExpCtx();
+    boost::intrusive_ptr<Expression> expression = ExpressionTestApiVersion::parse(
+        expCtx.get(),
+        BSON("$_testApiVersion" << BSON("unstable" << true)).firstElement(),
+        expCtx->variablesParseState);
+
+    ASSERT_VALUE_EQ(Value(DOC("$_testApiVersion" << DOC("unstable" << true))),
+                    expression->serialize(false));
+}
+
+TEST_F(TestApiVersion, UnstableDoesNotAcceptNumericValue) {
+    auto expCtx = getExpCtx();
+
+    ASSERT_THROWS_CODE(ExpressionTestApiVersion::parse(
+                           expCtx.get(),
+                           BSON("$_testApiVersion" << BSON("unstable" << 1)).firstElement(),
+                           expCtx->variablesParseState),
+                       AssertionException,
+                       5161702);
+}
+
+TEST_F(TestApiVersion, DeprecatedAcceptsBooleanValue) {
+    auto expCtx = getExpCtx();
+    boost::intrusive_ptr<Expression> expression = ExpressionTestApiVersion::parse(
+        expCtx.get(),
+        BSON("$_testApiVersion" << BSON("deprecated" << true)).firstElement(),
+        expCtx->variablesParseState);
+
+    ASSERT_VALUE_EQ(Value(DOC("$_testApiVersion" << DOC("deprecated" << true))),
+                    expression->serialize(false));
+}
+
+TEST_F(TestApiVersion, DeprecatedDoesNotAcceptNumericValue) {
+    auto expCtx = getExpCtx();
+
+    ASSERT_THROWS_CODE(ExpressionTestApiVersion::parse(
+                           expCtx.get(),
+                           BSON("$_testApiVersion" << BSON("deprecated" << 1)).firstElement(),
+                           expCtx->variablesParseState),
+                       AssertionException,
+                       5161703);
+}
+
+TEST_F(TestApiVersion, DoesNotAcceptInvalidParameter) {
+    auto expCtx = getExpCtx();
+
+    ASSERT_THROWS_CODE(
+        ExpressionTestApiVersion::parse(
+            expCtx.get(),
+            BSON("$_testApiVersion" << BSON("invalidParameter" << true)).firstElement(),
+            expCtx->variablesParseState),
+        AssertionException,
+        5161704);
+}
+
+TEST_F(TestApiVersion, OnlyTakesOneParameter) {
+    auto expCtx = getExpCtx();
+
+    ASSERT_THROWS_CODE(
+        ExpressionTestApiVersion::parse(
+            expCtx.get(),
+            BSON("$_testApiVersion" << BSON("deprecated" << true << "unstable" << true))
+                .firstElement(),
+            expCtx->variablesParseState),
+        AssertionException,
+        5161701);
+}
+
+TEST_F(TestApiVersion, DoesNotAcceptEmptyDocument) {
+    auto expCtx = getExpCtx();
+
+    ASSERT_THROWS_CODE(
+        ExpressionTestApiVersion::parse(expCtx.get(),
+                                        BSON("$_testApiVersion" << BSONObj()).firstElement(),
+                                        expCtx->variablesParseState),
+        AssertionException,
+        5161701);
+}
+}  // namespace
+}  // namespace mongo
\ No newline at end of file
diff --git a/src/mongo/db/pipeline/expression_visitor.h b/src/mongo/db/pipeline/expression_visitor.h
index de4b32908e3..51225289b26 100644
--- a/src/mongo/db/pipeline/expression_visitor.h
+++ b/src/mongo/db/pipeline/expression_visitor.h
@@ -117,6 +117,7 @@ class ExpressionBinarySize;
 class ExpressionStrLenCP;
 class ExpressionSubtract;
 class ExpressionSwitch;
+class ExpressionTestApiVersion;
 class ExpressionToLower;
 class ExpressionToUpper;
 class ExpressionTrim;
@@ -185,6 +186,7 @@ public:
     virtual void visit(ExpressionAllElementsTrue*) = 0;
     virtual void visit(ExpressionAnd*) = 0;
     virtual void visit(ExpressionAnyElementTrue*) = 0;
+    virtual void visit(ExpressionTestApiVersion*) = 0;
     virtual void visit(ExpressionArray*) = 0;
     virtual void visit(ExpressionArrayElemAt*) = 0;
     virtual void visit(ExpressionFirst*) = 0;