SERVER-10689 Aggregation now supports the switch expression.

2 files changed, 221 insertions, 0 deletions

diff --git a/jstests/aggregation/expressions/switch.js b/jstests/aggregation/expressions/switch.js
new file mode 100644
index 00000000000..9a6dbbb529d
--- /dev/null
+++ b/jstests/aggregation/expressions/switch.js
@@ -0,0 +1,150 @@
+// In SERVER-10689, the $switch expression was introduced. In this file, we test the functionality
+// of the expression.
+
+(function() {
+    "use strict";
+
+    var coll = db.switch;
+    coll.drop();
+
+    // Insert an empty document so that something can flow through the pipeline.
+    coll.insert({});
+
+    // Ensure that a branch is correctly evaluated.
+    var pipeline = {
+        "$project": {
+            "_id": 0,
+            "output": {
+                "$switch": {
+                    "branches": [{"case": {"$eq": [1, 1]}, "then": "one is equal to one!"}],
+                }
+            }
+        }
+    };
+    var res = coll.aggregate(pipeline).toArray();
+
+    assert.eq(res.length, 1);
+    assert.eq(res[0], {"output": "one is equal to one!"});
+
+    // Ensure that the first branch which matches is chosen.
+    pipeline = {
+        "$project": {
+            "_id": 0,
+            "output": {
+                "$switch": {
+                    "branches": [
+                        {"case": {"$eq": [1, 1]}, "then": "one is equal to one!"},
+                        {"case": {"$eq": [2, 2]}, "then": "two is equal to two!"}
+                    ],
+                }
+            }
+        }
+    };
+    res = coll.aggregate(pipeline).toArray();
+
+    assert.eq(res.length, 1);
+    assert.eq(res[0], {"output": "one is equal to one!"});
+
+    // Ensure that the default is chosen if no case matches.
+    pipeline = {
+        "$project": {
+            "_id": 0,
+            "output": {
+                "$switch": {
+                    "branches": [{"case": {"$eq": [1, 2]}, "then": "one is equal to two!"}],
+                    "default": "no case matched."
+                }
+            }
+        }
+    };
+    res = coll.aggregate(pipeline).toArray();
+
+    assert.eq(res.length, 1);
+    assert.eq(res[0], {"output": "no case matched."});
+
+    // Ensure that nullish values are treated as false when they are a "case", and are null
+    // otherwise.
+    pipeline = {
+        "$project": {
+            "_id": 0,
+            "output": {
+                "$switch": {
+                    "branches": [{"case": null, "then": "Null was true!"}],
+                    "default": "No case matched."
+                }
+            }
+        }
+    };
+    res = coll.aggregate(pipeline).toArray();
+
+    assert.eq(res.length, 1);
+    assert.eq(res[0], {"output": "No case matched."});
+
+    pipeline = {
+        "$project": {
+            "_id": 0,
+            "output": {
+                "$switch": {
+                    "branches": [{"case": "$missingField", "then": "Null was true!"}],
+                    "default": "No case matched."
+                }
+            }
+        }
+    };
+    res = coll.aggregate(pipeline).toArray();
+
+    assert.eq(res.length, 1);
+    assert.eq(res[0], {"output": "No case matched."});
+
+    pipeline = {
+        "$project": {
+            "_id": 0,
+            "output":
+                {"$switch": {"branches": [{"case": true, "then": null}], "default": false}}
+        }
+    };
+    res = coll.aggregate(pipeline).toArray();
+
+    assert.eq(res.length, 1);
+    assert.eq(res[0], {"output": null});
+
+    pipeline = {
+        "$project": {
+            "_id": 0,
+            "output": {
+                "$switch":
+                    {"branches": [{"case": true, "then": "$missingField"}], "default": false}
+            }
+        }
+    };
+    res = coll.aggregate(pipeline).toArray();
+
+    assert.eq(res.length, 1);
+    assert.eq(res[0], {});
+
+    pipeline = {
+        "$project": {
+            "_id": 0,
+            "output":
+                {"$switch": {"branches": [{"case": null, "then": false}], "default": null}}
+        }
+    };
+    res = coll.aggregate(pipeline).toArray();
+
+    assert.eq(res.length, 1);
+    assert.eq(res[0], {"output": null});
+
+    pipeline = {
+        "$project": {
+            "_id": 0,
+            "output": {
+                "$switch":
+                    {"branches": [{"case": null, "then": false}], "default": "$missingField"}
+            }
+        }
+    };
+    res = coll.aggregate(pipeline).toArray();
+
+    assert.eq(res.length, 1);
+    assert.eq(res[0], {});
+}());
diff --git a/jstests/aggregation/expressions/switch_errors.js b/jstests/aggregation/expressions/switch_errors.js
new file mode 100644
index 00000000000..cf6dc0f4f93
--- /dev/null
+++ b/jstests/aggregation/expressions/switch_errors.js
@@ -0,0 +1,71 @@
+// SERVER-10689 introduced the $switch expression. In this file, we test the error cases of the
+// expression.
+load("jstests/aggregation/extras/utils.js");  // For assertErrorCode.
+
+(function() {
+    "use strict";
+
+    var coll = db.switch;
+    coll.drop();
+
+    var pipeline = {
+        "$project": {"output": {"$switch": "not an object"}}
+    };
+    assertErrorCode(coll, pipeline, 40060, "$switch requires an object as an argument.");
+
+    pipeline = {
+        "$project": {"output": {"$switch": {"branches": "not an array"}}}
+    };
+    assertErrorCode(coll, pipeline, 40061, "$switch requires 'branches' to be an array.");
+
+    pipeline = {
+        "$project": {"output": {"$switch": {"branches": ["not an object"]}}}
+    };
+    assertErrorCode(coll, pipeline, 40062, "$switch requires each branch to be an object.");
+
+    pipeline = {
+        "$project": {"output": {"$switch": {"branches": [{}]}}}
+    };
+    assertErrorCode(coll, pipeline, 40064, "$switch requires each branch have a 'case'.");
+
+    pipeline = {
+        "$project": {
+            "output": {
+                "$switch": {
+                    "branches": [{
+                        "case": 1,
+                    }]
+                }
+            }
+        }
+    };
+    assertErrorCode(coll, pipeline, 40065, "$switch requires each branch have a 'then'.");
+
+    pipeline = {
+        "$project":
+            {"output": {"$switch": {"branches": [{"case": true, "then": false, "badKey": 1}]}}}
+    };
+    assertErrorCode(coll, pipeline, 40063, "$switch found a branch with an unknown argument");
+
+    pipeline = {
+        "$project": {"output": {"$switch": {"notAnArgument": 1}}}
+    };
+    assertErrorCode(coll, pipeline, 40067, "$switch found an unknown argument");
+
+    pipeline = {
+        "$project": {"output": {"$switch": {"branches": []}}}
+    };
+    assertErrorCode(coll, pipeline, 40068, "$switch requires at least one branch");
+
+    pipeline = {
+        "$project": {"output": {"$switch": {}}}
+    };
+    assertErrorCode(coll, pipeline, 40068, "$switch requires at least one branch");
+
+    coll.insert({x: 1});
+    pipeline = {
+        "$project":
+            {"output": {"$switch": {"branches": [{"case": {"$eq": ["$x", 0]}, "then": 1}]}}}
+    };
+    assertErrorCode(coll, pipeline, 40066, "$switch has no default and an input matched no case");
+}());