[jest-each] Fix pluralising missing arguments error

CHANGELOG.md

@@ -13,6 +13,7 @@
 
 ### Fixes
 
+- `[jest-each]` Fix pluralising missing arguments error ([#6369](https://github.com/facebook/jest/pull/6369))
 - `[jest-each]` Stop test title concatenating extra args ([#6346](https://github.com/facebook/jest/pull/6346))
 - `[expect]` toHaveBeenNthCalledWith/nthCalledWith gives wrong call messages if not matched ([#6340](https://github.com/facebook/jest/pull/6340))
 - `[jest-each]` Make sure invalid arguments to `each` points back to the user's code ([#6347](https://github.com/facebook/jest/pull/6347))

e2e/__tests__/__snapshots__/each.test.js.snap

@@ -47,9 +47,10 @@ exports[`runs only the describe.only.each tests 1`] = `
 
 exports[`shows error message when not enough arguments are supplied to tests 1`] = `
 "FAIL __tests__/each-exception.test.js
+  ✕ throws exception when one argument too few are supplied $left == $right
   ✕ throws exception when not enough arguments are supplied $left == $right
 
-  ● throws exception when not enough arguments are supplied $left == $right
+  ● throws exception when one argument too few are supplied $left == $right
 
     Not enough arguments supplied for given headings:
     left | right
@@ -61,7 +62,7 @@ exports[`shows error message when not enough arguments are supplied to tests 1`]
       true,
     ]
 
-    Missing 1 arguments
+    Missing 1 argument
 
        6 |  */
        7 | 
@@ -73,6 +74,29 @@ exports[`shows error message when not enough arguments are supplied to tests 1`]
 
       at __tests__/each-exception.test.js:8:1
 
+  ● throws exception when not enough arguments are supplied $left == $right
+
+    Not enough arguments supplied for given headings:
+    left | right | up | down
+
+    Received:
+    Array [
+      true,
+      true,
+    ]
+
+    Missing 2 arguments
+
+      17 | );
+      18 | 
+    > 19 | it.each\`
+         | ^
+      20 |   left    | right   | up | down
+      21 |   \${true} | \${true}
+      22 | \`(
+
+      at __tests__/each-exception.test.js:19:1
+
 "
 `;
 

e2e/each/__tests__/each-exception.test.js

@@ -9,6 +9,16 @@ it.each`
   left    | right
   ${true} | ${true}
   ${true}
+`(
+  'throws exception when one argument too few are supplied $left == $right',
+  ({left, right}) => {
+    expect(left).toBe(right);
+  }
+);
+
+it.each`
+  left    | right   | up | down
+  ${true} | ${true}
 `(
   'throws exception when not enough arguments are supplied $left == $right',
   ({left, right}) => {

packages/jest-each/src/bind.js

@@ -39,15 +39,20 @@ export default (cb: Function) => (...args: any) =>
     const keys = getHeadingKeys(templateStrings[0]);
     const table = buildTable(data, keys.length, keys);
 
-    if (data.length % keys.length !== 0) {
+    const missingData = data.length % keys.length;
+
+    if (missingData > 0) {
       const error = new Error(
         'Not enough arguments supplied for given headings:\n' +
           EXPECTED_COLOR(keys.join(' | ')) +
           '\n\n' +
           'Received:\n' +
           RECEIVED_COLOR(pretty(data)) +
           '\n\n' +
-          `Missing ${RECEIVED_COLOR(`${data.length % keys.length}`)} arguments`,
+          `Missing ${RECEIVED_COLOR(missingData.toString())} ${pluralize(
+            'argument',
+            missingData,
+          )}`,
       );
 
       if (Error.captureStackTrace) {
@@ -136,3 +141,6 @@ const applyObjectParams = (obj: any, test: Function) => {
 
   return () => test(obj);
 };
+
+const pluralize = (word: string, count: number) =>
+  word + (count === 1 ? '' : 's');