edenapi: make JSON representation of DataRequest into an object

Summary:
EdenAPI's `make_req` tools allows developers to create ad-hoc CBOR request payloads for debugging purposes (e.g., for use with `curl`). The tool generates requests from human-created JSON, which are particularly useful in Mercurial and Mononoke's integration tests.

Later in this stack, the use of this JSON format will be extended beyond just this one tool. As such, it is important that the representation be sufficiently extensible so accommodate future changes to the request structs. In the case of the JSON representation of `DataRequest`, this means changing from an array to a single-attribute object, so that additional fields can potentially be added in the future.

Reviewed By: quark-zju

Differential Revision: D22319314

fbshipit-source-id: 5931bc7ab01ca48ceab5ffd1c9177dd3035b643c

eden/mononoke/tests/integration/test-edenapi-server-files.t

@@ -33,10 +33,12 @@ Start up EdenAPI server.
 
 Create and send file data request.
   $ edenapi_make_req data > req.cbor <<EOF
-  > [
-  >    ["test.txt", "$TEST_FILENODE"],
-  >    ["copy.txt", "$COPY_FILENODE"]
-  > ]
+  > {
+  >   "keys": [
+  >     ["test.txt", "$TEST_FILENODE"],
+  >     ["copy.txt", "$COPY_FILENODE"]
+  >   ]
+  > }
   > EOF
   Reading from stdin
   Generated request: DataRequest {

eden/mononoke/tests/integration/test-edenapi-server-trees.t

@@ -33,10 +33,12 @@ Start up EdenAPI server.
 
 Create and send tree request.
   $ edenapi_make_req data > req.cbor <<EOF
-  > [
-  >    ["", "$ROOT_MFID_1"],
-  >    ["", "$ROOT_MFID_2"]
-  > ]
+  > {
+  >   "keys": [
+  >     ["", "$ROOT_MFID_1"],
+  >     ["", "$ROOT_MFID_2"]
+  >   ]
+  > }
   > EOF
   Reading from stdin
   Generated request: DataRequest {

eden/scm/lib/edenapi/tools/make_req/src/main.rs

@@ -68,16 +68,25 @@ fn main() -> Result<()> {
 /// Example request:
 ///
 ///     ```json
-///     [
-///       ["path/to/file_1", "48f43af456d770b6a78e1ace628319847e05cc24"],
-///       ["path/to/file_2", "7dcd6ede35eaaa5b1b16a341b19993e59f9b0dbf"],
-///       ["path/to/file_3", "218d708a9f8c3e37cfd7ab916c537449ac5419cd"],
-///     ]
+///     {
+///       "keys": [
+///         ["path/to/file_1", "48f43af456d770b6a78e1ace628319847e05cc24"],
+///         ["path/to/file_2", "7dcd6ede35eaaa5b1b16a341b19993e59f9b0dbf"],
+///         ["path/to/file_3", "218d708a9f8c3e37cfd7ab916c537449ac5419cd"],
+///       ]
+///     }
 ///     ```
 ///
 fn parse_data_req(json: &Value) -> Result<DataRequest> {
+    let json = json
+        .as_object()
+        .ok_or_else(|| anyhow!("input must be a JSON object"))?;
+    let keys = json
+        .get("keys")
+        .ok_or_else(|| anyhow!("missing field: keys"))?;
+
     Ok(DataRequest {
-        keys: parse_keys(json)?,
+        keys: parse_keys(keys)?,
     })
 }