[jest-each]: Add support for keyPaths in test titles

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## master
 
+### Features
+
+- `[jest-each]` Add support for keyPaths in test titles ([#6457](https://github.com/facebook/jest/pull/6457/files))
+
 ### Fixes
 
 - `[jest-config]` Add missing options to the `defaults` object ([#6428](https://github.com/facebook/jest/pull/6428))

docs/GlobalAPI.md

@@ -271,6 +271,7 @@ describe.each([[1, 1, 2], [1, 2, 3], [2, 1, 3]])(
   - First row of variable name column headings separated with `|`
   - One or more subsequent rows of data supplied as template literal expressions using `${value}` syntax.
 - `name`: `String` the title of the test suite, use `$variable` to inject test data into the suite title from the tagged template expressions.
+  - To inject nested object values use you can supply a keyPath i.e. `$variable.path.to.value`
 - `fn`: `Function` the suite of tests to be ran, this is the function that will receive the test data object.
 
 Example:
@@ -507,6 +508,7 @@ test.each([[1, 1, 2], [1, 2, 3], [2, 1, 3]])(
   - First row of variable name column headings separated with `|`
   - One or more subsequent rows of data supplied as template literal expressions using `${value}` syntax.
 - `name`: `String` the title of the test, use `$variable` to inject test data into the test title from the tagged template expressions.
+  - To inject nested object values use you can supply a keyPath i.e. `$variable.path.to.value`
 - `fn`: `Function` the test to be ran, this is the function that will receive the test data object.
 
 Example:

packages/jest-each/README.md

@@ -271,6 +271,7 @@ each`
 ##### `.test`:
 
 - name: `String` the title of the `test`, use `$variable` in the name string to inject test values into the test title from the tagged template expressions
+  - To inject nested object values use you can supply a keyPath i.e. `$variable.path.to.value`
 - testFn: `Function` the test logic, this is the function that will receive the parameters of each row as function arguments
 
 #### `each[tagged template].describe(name, suiteFn)`
@@ -306,6 +307,7 @@ each`
 ##### `.describe`:
 
 - name: `String` the title of the `test`, use `$variable` in the name string to inject test values into the test title from the tagged template expressions
+  - To inject nested object values use you can supply a keyPath i.e. `$variable.path.to.value`
 - suiteFn: `Function` the suite of `test`/`it`s to be ran, this is the function that will receive the parameters in each row as function arguments
 
 ### Usage

packages/jest-each/src/__tests__/template.test.js

@@ -138,7 +138,66 @@ describe('jest-each', () => {
         );
       });
 
-      test('calls global with cb function with object built from tabel headings and values', () => {
+      test('calls global with title containing $key in multiple positions', () => {
+        const globalTestMocks = getGlobalTestMocks();
+        const eachObject = each.withGlobal(globalTestMocks)`
+          a    | b    | expected
+          ${0} | ${1} | ${1}
+          ${1} | ${1} | ${2}
+        `;
+        const testFunction = get(eachObject, keyPath);
+        testFunction(
+          'add($a, $b) expected string: a=$a, b=$b, expected=$expected',
+          noop,
+        );
+
+        const globalMock = get(globalTestMocks, keyPath);
+        expect(globalMock).toHaveBeenCalledTimes(2);
+        expect(globalMock).toHaveBeenCalledWith(
+          'add(0, 1) expected string: a=0, b=1, expected=1',
+          expectFunction,
+        );
+        expect(globalMock).toHaveBeenCalledWith(
+          'add(1, 1) expected string: a=1, b=1, expected=2',
+          expectFunction,
+        );
+      });
+
+      test('calls global with title containing $key.path', () => {
+        const globalTestMocks = getGlobalTestMocks();
+        const eachObject = each.withGlobal(globalTestMocks)`
+          a
+          ${{foo: {bar: 'baz'}}}
+        `;
+        const testFunction = get(eachObject, keyPath);
+        testFunction('interpolates object keyPath to value: $a.foo.bar', noop);
+
+        const globalMock = get(globalTestMocks, keyPath);
+        expect(globalMock).toHaveBeenCalledTimes(1);
+        expect(globalMock).toHaveBeenCalledWith(
+          'interpolates object keyPath to value: "baz"',
+          expectFunction,
+        );
+      });
+
+      test('calls global with title containing last seen object when $key.path is invalid', () => {
+        const globalTestMocks = getGlobalTestMocks();
+        const eachObject = each.withGlobal(globalTestMocks)`
+          a
+          ${{foo: {bar: 'baz'}}}
+        `;
+        const testFunction = get(eachObject, keyPath);
+        testFunction('interpolates object keyPath to value: $a.foo.qux', noop);
+
+        const globalMock = get(globalTestMocks, keyPath);
+        expect(globalMock).toHaveBeenCalledTimes(1);
+        expect(globalMock).toHaveBeenCalledWith(
+          'interpolates object keyPath to value: {"bar": "baz"}',
+          expectFunction,
+        );
+      });
+
+      test('calls global with cb function with object built from table headings and values', () => {
         const globalTestMocks = getGlobalTestMocks();
         const testCallBack = jest.fn();
         const eachObject = each.withGlobal(globalTestMocks)`

packages/jest-each/src/bind.js

@@ -129,12 +129,19 @@ const buildTable = (
       ),
     );
 
+const getMatchingKeyPaths = title => (matches, key) =>
+  matches.concat(title.match(new RegExp(`\\$${key}[\\.\\w]*`, 'g')) || []);
+
+const replaceKeyPathWithValue = data => (title, match) => {
+  const keyPath = match.replace('$', '').split('.');
+  const value = getPath(data, keyPath);
+  return title.replace(match, pretty(value, {maxDepth: 1, min: true}));
+};
+
 const interpolate = (title: string, data: any) =>
-  Object.keys(data).reduce(
-    (acc, key) =>
-      acc.replace('$' + key, pretty(data[key], {maxDepth: 1, min: true})),
-    title,
-  );
+  Object.keys(data)
+    .reduce(getMatchingKeyPaths(title), []) // aka flatMap
+    .reduce(replaceKeyPathWithValue(data), title);
 
 const applyObjectParams = (obj: any, test: Function) => {
   if (test.length > 1) return done => test(obj, done);
@@ -144,3 +151,8 @@ const applyObjectParams = (obj: any, test: Function) => {
 
 const pluralize = (word: string, count: number) =>
   word + (count === 1 ? '' : 's');
+
+const getPath = (o: Object, [head, ...tail]: Array<string>) => {
+  if (!head || !o.hasOwnProperty || !o.hasOwnProperty(head)) return o;
+  return getPath(o[head], tail);
+};