[fp-rs] Split fetcher.rs into directory module, added mock.

fastpair/rust/demo/rust/src/advertisement.rs

@@ -16,7 +16,7 @@ use bluetooth::{BleAddress, BleAdvertisement, ServiceData};
 
 use crate::{
     decoder::FpDecoder,
-    fetcher::{FpFetcher, FpFetcherLocal},
+    fetcher::{DeviceInfo, FpFetcher, FpFetcherFs},
 };
 
 /// Represents a FP device model ID.
@@ -78,7 +78,7 @@ impl FpPairingAdvertisement {
         let model_id = format!("{}", u32::from_be_bytes(model_id.try_into().unwrap()));
 
         // Retrieve device info of the device corresponding to this model ID.
-        let fetcher = FpFetcherLocal::new(String::from("./local"));
+        let fetcher = FpFetcherFs::new(String::from("./local"));
         let device_info = fetcher
             .get_device_info_from_model_id(&model_id)
             .expect("Failed to create device info from model ID.");

fastpair/rust/demo/rust/src/fetcher/common.rs

@@ -11,27 +11,11 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
-use std::fs;
 
 use serde::Deserialize;
 
 use crate::advertisement::ModelId;
 
-/// Holds Fast Pair device information parsed from JSON.
-#[derive(Deserialize)]
-#[serde(rename_all = "camelCase")]
-pub(crate) struct DeviceInfo {
-    image_url: String,
-    name: String,
-}
-
-/// Holds top-level Fast Pair information parsed from JSON. See `local`
-/// directory for format.
-#[derive(Deserialize)]
-struct JsonData {
-    device: DeviceInfo,
-}
-
 /// Types that can fetch Fast Pair data from external storage (e.g. filesystem,
 /// remote server).
 pub(crate) trait FpFetcher {
@@ -41,36 +25,26 @@ pub(crate) trait FpFetcher {
     ) -> Result<DeviceInfo, anyhow::Error>;
 }
 
-/// A unit struct for retrieving Fast Pair information from the local filesystem.
-pub(crate) struct FpFetcherLocal {
-    path: String,
+/// Holds Fast Pair device information parsed from JSON.
+#[derive(Clone, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub(crate) struct DeviceInfo {
+    image_url: String,
+    name: String,
 }
 
-impl FpFetcherLocal {
-    pub(crate) fn new(path: String) -> Self {
-        FpFetcherLocal { path }
-    }
-}
-
-impl FpFetcher for FpFetcherLocal {
-    /// Retrieve device information for the provided Model ID. Currently,
-    /// this information is saved locally. In the future, this should instead
-    /// be retrieved from a remote server and cached.
-    /// b/294456411
-    fn get_device_info_from_model_id(
-        &self,
-        model_id: &ModelId,
-    ) -> Result<DeviceInfo, anyhow::Error> {
-        let file_path = format!("{}/{}.json", self.path, model_id);
-        let contents = fs::read_to_string(file_path).expect("Couldn't find or open file.");
-
-        let model_info: JsonData = serde_json::from_str(&contents)?;
-
-        Ok(model_info.device)
-    }
+/// Holds top-level Fast Pair information parsed from JSON. See `local`
+/// directory for format.
+#[derive(Deserialize)]
+pub(super) struct JsonData {
+    device: DeviceInfo,
 }
 
 impl DeviceInfo {
+    pub(crate) fn new(image_url: String, name: String) -> Self {
+        DeviceInfo { image_url, name }
+    }
+
     pub(crate) fn name(&self) -> &String {
         &self.name
     }
@@ -79,3 +53,10 @@ impl DeviceInfo {
         &self.image_url
     }
 }
+
+impl JsonData {
+    // Returns the `DeviceInfo` associated with parsed self, consuming self.
+    pub(super) fn device(self) -> DeviceInfo {
+        self.device
+    }
+}

fastpair/rust/demo/rust/src/fetcher/fs.rs

@@ -0,0 +1,49 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::fs;
+
+use crate::{
+    advertisement::ModelId,
+    fetcher::{DeviceInfo, FpFetcher, JsonData},
+};
+
+/// A struct for retrieving Fast Pair information from the local filesystem.
+pub(crate) struct FpFetcherFs {
+    path: String,
+}
+
+impl FpFetcherFs {
+    pub(crate) fn new(path: String) -> Self {
+        FpFetcherFs { path }
+    }
+}
+
+impl FpFetcher for FpFetcherFs {
+    /// Retrieve device information for the provided Model ID. Currently,
+    /// this information is saved locally. In the future, this should instead
+    /// be retrieved from a remote server and cached.
+    /// b/294456411
+    fn get_device_info_from_model_id(
+        &self,
+        model_id: &ModelId,
+    ) -> Result<DeviceInfo, anyhow::Error> {
+        let file_path = format!("{}/{}.json", self.path, model_id);
+        let contents = fs::read_to_string(file_path).expect("Couldn't find or open file.");
+
+        let model_info: JsonData = serde_json::from_str(&contents)?;
+
+        Ok(model_info.device())
+    }
+}

fastpair/rust/demo/rust/src/fetcher/mock.rs

@@ -0,0 +1,43 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use crate::{
+    advertisement::ModelId,
+    fetcher::{DeviceInfo, FpFetcher},
+};
+
+/// A struct for mocking retrieval of Fast Pair data.
+pub(crate) struct FpFetcherMock {
+    get_device_info_from_model_id: Result<DeviceInfo, anyhow::Error>,
+}
+
+impl FpFetcherMock {
+    pub(crate) fn new(get_device_info_from_model_id: Result<DeviceInfo, anyhow::Error>) -> Self {
+        FpFetcherMock {
+            get_device_info_from_model_id,
+        }
+    }
+}
+
+impl FpFetcher for FpFetcherMock {
+    fn get_device_info_from_model_id(
+        &self,
+        _model_id: &ModelId,
+    ) -> Result<DeviceInfo, anyhow::Error> {
+        match &self.get_device_info_from_model_id {
+            Ok(result) => Ok(result.clone()),
+            Err(_) => Err(anyhow::anyhow!("intentional mock error")),
+        }
+    }
+}

fastpair/rust/demo/rust/src/fetcher/mod.rs

@@ -0,0 +1,22 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+pub(crate) mod common;
+pub(crate) mod fs;
+
+#[cfg(test)]
+pub(crate) mod mock;
+
+pub(crate) use common::*;
+pub(crate) use fs::*;