Allow to override toolchain from rust-toolchain file (#35)

__tests__/args.test.ts

@@ -1,22 +1,57 @@
-import * as args from '../src/args'
-
-const testEnvVars = {
-    INPUT_TOOLCHAIN: 'nightly-2019-04-20',
-    INPUT_DEFAULT: 'false',
-    INPUT_OVERRIDE: 'true'
-}
+import {toolchain_args} from "../src/args";
+import {morph} from "mock-env"
+import {sync as tempWriteSync} from "temp-write"
 
 describe('actions-rs/toolchain', () => {
-    beforeEach(() => {
-    for (const key in testEnvVars)
-        process.env[key] = testEnvVars[key as keyof typeof testEnvVars]
-    })
-
     it('Parses action input into toolchain options', async () => {
-        const result = args.toolchain_args();
+        let args = morph(() => {
+            return toolchain_args("./rust-toolchain");
+        }, {
+            'INPUT_TOOLCHAIN': 'nightly-2019-04-20',
+            'INPUT_DEFAULT': 'false',
+            'INPUT_OVERRIDE': 'true'
+        });
 
-        expect(result.name).toBe('nightly-2019-04-20');
-        expect(result.default).toBe(false);
-        expect(result.override).toBe(true);
+        expect(args.name).toBe('nightly-2019-04-20');
+        expect(args.default).toBe(false);
+        expect(args.override).toBe(true);
+    });
+
+    it('uses input variable if rust-toolchain file does not exist', function () {
+        let args = morph(() => {
+            return toolchain_args("./rust-toolchain");
+        }, {
+            'INPUT_TOOLCHAIN': 'nightly',
+        });
+
+        expect(args.name).toBe("nightly")
+    });
+
+    it('toolchain input is required if rust-toolchain does not exist', function () {
+        expect(() => toolchain_args("./rust-toolchain")).toThrowError()
+    });
+
+    it('prioritizes rust-toolchain file over input variable', function () {
+        let rustToolchainFile = tempWriteSync("1.39.0");
+
+        let args = morph(() => {
+            return toolchain_args(rustToolchainFile);
+        }, {
+            'INPUT_TOOLCHAIN': 'nightly',
+        });
+
+        expect(args.name).toBe("1.39.0")
+    });
+
+    it('trims content of the override file', function () {
+        let rustToolchainFile = tempWriteSync("\n     1.39.0\n\n\n\n");
+
+        let args = morph(() => {
+            return toolchain_args(rustToolchainFile);
+        }, {
+            'INPUT_TOOLCHAIN': 'nightly',
+        });
+
+        expect(args.name).toBe("1.39.0")
     });
 });