feat: add readJson/readJsonSync for fs modules

fs/read_json.ts

@@ -0,0 +1,42 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import * as path from "./path/mod.ts";
+
+/**
+ * Reads a JSON file and then parses it into an object
+ * @export
+ * @param {string} filePath
+ * @returns {Promise<any>}
+ */
+export async function readJson(filePath: string): Promise<any> {
+  filePath = path.resolve(filePath);
+  const decoder = new TextDecoder("utf-8");
+
+  const content = decoder.decode(await Deno.readFile(filePath));
+
+  try {
+    return JSON.parse(content);
+  } catch (err) {
+    err.message = `${filePath}: ${err.message}`;
+    throw err;
+  }
+}
+
+/**
+ * Reads a JSON file and then parses it into an object
+ * @export
+ * @param {string} filePath
+ * @returns {void}
+ */
+export function readJsonSync(filePath: string): any {
+  filePath = path.resolve(filePath);
+  const decoder = new TextDecoder("utf-8");
+
+  const content = decoder.decode(Deno.readFileSync(filePath));
+
+  try {
+    return JSON.parse(content);
+  } catch (err) {
+    err.message = `${filePath}: ${err.message}`;
+    throw err;
+  }
+}

fs/read_json_test.ts

@@ -0,0 +1,91 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import { test } from "../testing/mod.ts";
+import {
+  assertEquals,
+  assertThrowsAsync,
+  assertThrows
+} from "../testing/asserts.ts";
+import { readJson, readJsonSync } from "./read_json.ts";
+import * as path from "./path/mod.ts";
+
+const testdataDir = path.resolve("fs", "testdata");
+
+test(async function readJsonFileNotExists() {
+  const emptyJsonFile = path.join(testdataDir, "json_not_exists.json");
+
+  await assertThrowsAsync(async () => {
+    await readJson(emptyJsonFile);
+  });
+});
+
+test(async function readEmptyJsonFile() {
+  const emptyJsonFile = path.join(testdataDir, "json_empty.json");
+
+  await assertThrowsAsync(async () => {
+    await readJson(emptyJsonFile);
+  });
+});
+
+test(async function readInvalidJsonFile() {
+  const invalidJsonFile = path.join(testdataDir, "json_invalid.json");
+
+  await assertThrowsAsync(async () => {
+    await readJson(invalidJsonFile);
+  });
+});
+
+test(async function readValidJsonFile() {
+  const invalidJsonFile = path.join(testdataDir, "json_valid_array.json");
+
+  const json = await readJson(invalidJsonFile);
+
+  assertEquals(json, ["1", "2", "3"]);
+});
+
+test(async function readValidJsonFile() {
+  const invalidJsonFile = path.join(testdataDir, "json_valid_obj.json");
+
+  const json = await readJson(invalidJsonFile);
+
+  assertEquals(json, { key1: "value1", key2: "value2" });
+});
+
+test(function readJsonFileNotExistsSync() {
+  const emptyJsonFile = path.join(testdataDir, "json_not_exists.json");
+
+  assertThrows(() => {
+    readJsonSync(emptyJsonFile);
+  });
+});
+
+test(function readEmptyJsonFileSync() {
+  const emptyJsonFile = path.join(testdataDir, "json_empty.json");
+
+  assertThrows(() => {
+    readJsonSync(emptyJsonFile);
+  });
+});
+
+test(function readInvalidJsonFile() {
+  const invalidJsonFile = path.join(testdataDir, "json_invalid.json");
+
+  assertThrows(() => {
+    readJsonSync(invalidJsonFile);
+  });
+});
+
+test(function readValidJsonFile() {
+  const invalidJsonFile = path.join(testdataDir, "json_valid_array.json");
+
+  const json = readJsonSync(invalidJsonFile);
+
+  assertEquals(json, ["1", "2", "3"]);
+});
+
+test(function readValidJsonFile() {
+  const invalidJsonFile = path.join(testdataDir, "json_valid_obj.json");
+
+  const json = readJsonSync(invalidJsonFile);
+
+  assertEquals(json, { key1: "value1", key2: "value2" });
+});

fs/testdata/json_invalid.json

@@ -0,0 +1,5 @@
+{
+  [
+    "here is a invalid json file"
+  ]
+}

fs/testdata/json_valid_array.json

@@ -0,0 +1,5 @@
+[
+  "1",
+  "2",
+  "3"
+]

fs/testdata/json_valid_obj.json

@@ -0,0 +1,4 @@
+{
+  "key1": "value1",
+  "key2": "value2"
+}

test.ts

@@ -18,6 +18,7 @@ import "./fs/empty_dir_test.ts";
 import "./fs/ensure_dir_test.ts";
 import "./fs/ensure_file_test.ts";
 import "./fs/move_test.ts";
+import "./fs/read_json_test.ts";
 import "./io/test.ts";
 import "./http/server_test.ts";
 import "./http/file_server_test.ts";