Fix detection of non-existent commands

src/linters/black.js

@@ -1,5 +1,5 @@
-const commandExists = require("../../vendor/command-exists");
 const { run } = require("../utils/action");
+const commandExists = require("../utils/command-exists");
 const { parseErrorsFromDiff } = require("../utils/diff");
 const { initLintResult } = require("../utils/lint-result");
 

src/linters/eslint.js

@@ -1,5 +1,5 @@
-const commandExists = require("../../vendor/command-exists");
 const { run } = require("../utils/action");
+const commandExists = require("../utils/command-exists");
 const { initLintResult } = require("../utils/lint-result");
 const { getNpmBinCommand } = require("../utils/npm/get-npm-bin-command");
 const { removeTrailingPeriod } = require("../utils/string");

src/linters/flake8.js

@@ -1,7 +1,7 @@
 const { sep } = require("path");
 
-const commandExists = require("../../vendor/command-exists");
 const { log, run } = require("../utils/action");
+const commandExists = require("../utils/command-exists");
 const { initLintResult } = require("../utils/lint-result");
 const { capitalizeFirstLetter } = require("../utils/string");
 

src/linters/gofmt.js

@@ -1,5 +1,5 @@
-const commandExists = require("../../vendor/command-exists");
 const { run } = require("../utils/action");
+const commandExists = require("../utils/command-exists");
 const { parseErrorsFromDiff } = require("../utils/diff");
 const { initLintResult } = require("../utils/lint-result");
 

src/linters/golint.js

@@ -1,5 +1,5 @@
-const commandExists = require("../../vendor/command-exists");
 const { log, run } = require("../utils/action");
+const commandExists = require("../utils/command-exists");
 const { initLintResult } = require("../utils/lint-result");
 const { capitalizeFirstLetter } = require("../utils/string");
 

src/linters/mypy.js

@@ -1,8 +1,8 @@
 const fs = require("fs");
 const { sep } = require("path");
 
-const commandExists = require("../../vendor/command-exists");
 const { log, run } = require("../utils/action");
+const commandExists = require("../utils/command-exists");
 const { initLintResult } = require("../utils/lint-result");
 
 const PARSE_REGEX = /^(.*):([0-9]+): (\w*): (.*)$/gm;

src/linters/prettier.js

@@ -1,5 +1,5 @@
-const commandExists = require("../../vendor/command-exists");
 const { run } = require("../utils/action");
+const commandExists = require("../utils/command-exists");
 const { initLintResult } = require("../utils/lint-result");
 const { getNpmBinCommand } = require("../utils/npm/get-npm-bin-command");
 

src/linters/rubocop.js

@@ -1,5 +1,5 @@
-const commandExists = require("../../vendor/command-exists");
 const { run } = require("../utils/action");
+const commandExists = require("../utils/command-exists");
 const { initLintResult } = require("../utils/lint-result");
 const { removeTrailingPeriod } = require("../utils/string");
 

src/linters/stylelint.js

@@ -1,5 +1,5 @@
-const commandExists = require("../../vendor/command-exists");
 const { run } = require("../utils/action");
+const commandExists = require("../utils/command-exists");
 const { initLintResult } = require("../utils/lint-result");
 const { getNpmBinCommand } = require("../utils/npm/get-npm-bin-command");
 

src/linters/swift-format-lockwood.js

@@ -1,5 +1,5 @@
-const commandExists = require("../../vendor/command-exists");
 const { run } = require("../utils/action");
+const commandExists = require("../utils/command-exists");
 const { initLintResult } = require("../utils/lint-result");
 
 const PARSE_REGEX = /^(.*):([0-9]+):[0-9]+: \w+: \((\w+)\) (.*)\.$/gm;

src/linters/swift-format-official.js

@@ -1,5 +1,5 @@
-const commandExists = require("../../vendor/command-exists");
 const { run } = require("../utils/action");
+const commandExists = require("../utils/command-exists");
 const { initLintResult } = require("../utils/lint-result");
 
 const PARSE_REGEX = /^(.*):([0-9]+):([0-9]+): (warning|error): (.*)$/gm;

src/linters/swiftlint.js

@@ -1,5 +1,5 @@
-const commandExists = require("../../vendor/command-exists");
 const { run } = require("../utils/action");
+const commandExists = require("../utils/command-exists");
 const { initLintResult } = require("../utils/lint-result");
 
 const PARSE_REGEX = /^(.*):([0-9]+):[0-9]+: (warning|error): (.*)$/gm;

src/linters/xo.js

@@ -1,5 +1,5 @@
-const commandExists = require("../../vendor/command-exists");
 const { run } = require("../utils/action");
+const commandExists = require("../utils/command-exists");
 const { getNpmBinCommand } = require("../utils/npm/get-npm-bin-command");
 const ESLint = require("./eslint");
 

src/utils/command-exists.js

@@ -0,0 +1,19 @@
+const checkForCommand = require("../../vendor/command-exists");
+
+/**
+ * Returns whether the provided shell command is available
+ * @param {string} command - Shell command to check for
+ * @returns {Promise<boolean>} - Whether the command is available
+ */
+async function commandExists(command) {
+	// The `command-exists` library throws an error if the command is not available. This function
+	// catches these errors and returns a boolean value instead
+	try {
+		await checkForCommand(command);
+		return true;
+	} catch (error) {
+		return false;
+	}
+}
+
+module.exports = commandExists;

test/utils/command-exists.test.js

@@ -0,0 +1,11 @@
+const commandExists = require("../../src/utils/command-exists");
+
+describe("commandExists()", () => {
+	test("should return `true` for existing command", async () => {
+		await expect(commandExists("cat")).resolves.toEqual(true);
+	});
+
+	test("should return `false` for non-existent command", async () => {
+		await expect(commandExists("nonexistentcommand")).resolves.toEqual(false);
+	});
+});