Add toBeArrayWithFloats matcher

.all-contributorsrc

@@ -450,6 +450,17 @@
       "contributions": [
         "code"
       ]
+    },
+    {
+      "login": "danielpmichalski",
+      "name": "Daniel Michalski",
+      "avatar_url": "https://avatars2.githubusercontent.com/u/5457711?v=4",
+      "profile": "https://twitter.com/crazyPolishDan",
+      "contributions": [
+        "code",
+        "doc",
+        "test"
+      ]
     }
   ],
   "repoType": "github"

README.md

@@ -48,6 +48,7 @@ If you've come here to help contribute - Thanks! Take a look at the [contributin
   - [Array](#array)
     - [.toBeArray()](#tobearray)
     - [.toBeArrayOfSize()](#tobearrayofsize)
+    - [.toBeArrayWithFloats([members], ?precision)](#tobearraywithfloatsmembers-precision)
     - [.toIncludeAllMembers([members])](#toincludeallmembersmembers)
     - [.toIncludeAnyMembers([members])](#toincludeanymembersmembers)
     - [.toIncludeSameMembers([members])](#toincludesamemembersmembers)
@@ -272,6 +273,17 @@ test('passes when value is an array', () => {
 });
 ```
 
+#### .toBeArrayWithFloats([members], ?precision)
+
+Use `.toBeArrayWithFloats` when comparing arrays of floating-point numbers with chosen precision in the same order.
+
+```js
+test('passes when arrays have same floats', () => {
+  expect([1.11112, 2.22221]).toBeArrayWithFloats([1.11114, 2.22223]); // default 4-digit decimal precision
+  expect([1.112]).not.toBeArrayWithFloats([1.111], 3); // specified 3-digit decimal precision
+});
+```
+
 #### .toIncludeAllMembers([members])
 
 Use `.toIncludeAllMembers` when checking if an `Array` contains all of the same members of a given set.
@@ -927,7 +939,7 @@ test('passes when value includes all substrings', () => {
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 <!-- ALL-CONTRIBUTORS-LIST:END -->
 
 ## LICENSE

src/matchers/toBeArrayWithFloats/index.js

@@ -0,0 +1,18 @@
+import predicate from './predicate';
+
+export default {
+  toBeArrayWithFloats: (received, expected, precision = 4) => {
+    const pass = predicate(received, expected, precision);
+    if (pass) {
+      return {
+        message: `expected [${received}] not to be equal to [${expected}] with ${precision}-digit precision`,
+        pass: true
+      };
+    } else {
+      return {
+        message: `expected [${received}] to be equal to [${expected}] with ${precision}-digit precision`,
+        pass: false
+      };
+    }
+  }
+};

src/matchers/toBeArrayWithFloats/index.test.js

@@ -0,0 +1,31 @@
+import matcher from './';
+
+expect.extend(matcher);
+
+describe('.toBeArrayWithFloats', () => {
+  test('passes for empty arrays', () => {
+    expect([]).toBeArrayWithFloats([]);
+  });
+
+  test('passes for arrays with same floats with default precision', () => {
+    expect([1.2, 2.45]).toBeArrayWithFloats([1.2, 2.45001]);
+  });
+
+  test('passes for arrays with floats rounded to same value with default precision', () => {
+    expect([0.00011]).toBeArrayWithFloats([0.0001]);
+  });
+
+  test('passes for arrays with same floats with specified precision', () => {
+    expect([1.014, 1.23456]).toBeArrayWithFloats([1.0104, 1.23112], 2);
+  });
+});
+
+describe('.not.toBeArrayWithFloats', () => {
+  test('passes for arrays with different floats', () => {
+    expect([1.0]).not.toBeArrayWithFloats([1.0001]);
+  });
+
+  test('passes for arrays with different floats due to rounding', () => {
+    expect([1.0]).not.toBeArrayWithFloats([1.00005]);
+  });
+});

src/matchers/toBeArrayWithFloats/predicate.js

@@ -0,0 +1,54 @@
+const isUndefined = function(obj) {
+  return typeof obj === 'undefined';
+};
+
+const someUndefined = function(objects) {
+  let check = false;
+  objects.forEach(item => (check = check || isUndefined(item)));
+  return check;
+};
+
+const areArrays = function(...objects) {
+  if (someUndefined(objects)) {
+    return false;
+  }
+
+  let allArrays = true;
+  objects.forEach(item => (allArrays = allArrays && Array.isArray(item)));
+  return allArrays;
+};
+
+const cutDecimals = function(num, precision) {
+  return Number.parseFloat(Number.parseFloat(num).toFixed(precision));
+};
+
+const floatsEqual = function(float1, float2, precision) {
+  let a = cutDecimals(float1, precision);
+  let b = cutDecimals(float2, precision);
+
+  if (a === 0 && b === 0) {
+    return true;
+  } else if (a !== 0 && b === 0) {
+    return false;
+  } else {
+    return a / b === 1;
+  }
+};
+
+const arrayWithFloatsEquals = function(array1, array2, precision) {
+  if (array1.length !== array2.length) {
+    return false;
+  }
+
+  for (let i = 0; i < array1.length; i++) {
+    if (!floatsEqual(array1[i], array2[i], precision)) {
+      return false;
+    }
+  }
+
+  return true;
+};
+
+export default (actual, expected, precision = 4) => {
+  return areArrays(actual, expected) && arrayWithFloatsEquals(actual, expected, precision);
+};

src/matchers/toBeArrayWithFloats/predicate.test.js

@@ -0,0 +1,74 @@
+import predicate from './predicate';
+
+describe('toBeArrayWithFloats predicate - positive test cases', () => {
+  test('returns true for empty arrays', () => {
+    expect(predicate([], [])).toBe(true);
+  });
+
+  test('returns true for arrays with zeroes', () => {
+    expect(predicate([0.0], [0.0])).toBe(true);
+  });
+
+  test('processes equal arrays with zeroes', () => {
+    expect(predicate([0.0, 1.0], [0.0, 1.0])).toBe(true);
+  });
+
+  test('returns true for arrays with same floats with default precision', () => {
+    expect(predicate([1.0001, 2.123], [1.00011, 2.123])).toBe(true);
+  });
+
+  test('returns true for arrays with same floats with specified precision', () => {
+    expect(predicate([1.231, 2.344], [1.23, 2.34], 2)).toBe(true);
+  });
+
+  test('returns true when floats do not differ after rounding', () => {
+    expect(predicate([1.0001], [1.00014])).toBe(true);
+  });
+});
+
+describe('toBeArrayWithFloats predicate - negative test cases', () => {
+  test('returns false for undefined objects', () => {
+    expect(predicate(undefined, undefined)).toBe(false);
+  });
+
+  test('returns false for comparing an array to undefined objects', () => {
+    expect(predicate([], undefined)).toBe(false);
+  });
+
+  test('returns false for comparing an array to undefined objects no.2', () => {
+    expect(predicate(undefined, [])).toBe(false);
+  });
+
+  test('returns false when one value is non-array', () => {
+    expect(predicate([1.0], 'non-array')).toBe(false);
+    expect(predicate('non-array', [1.0])).toBe(false);
+  });
+
+  test('returns false for non-array values', () => {
+    expect(predicate('string', 5)).toBe(false);
+  });
+
+  test('processes non-equal arrays with zeroes', () => {
+    expect(predicate([0, 1.0], [0, 0])).toBe(false);
+  });
+
+  test('processes non-equal arrays with zeroes in 2nd array', () => {
+    expect(predicate([1.0], [0])).toBe(false);
+  });
+
+  test('returns false when comparing arrays of different size', () => {
+    expect(predicate([1.0], [1.0, 2.0])).toBe(false);
+  });
+
+  test('returns false for arrays with different floats with default precision', () => {
+    expect(predicate([1.1111], [1.1112])).toBe(false);
+  });
+
+  test('returns false for arrays with different floats with specified precision', () => {
+    expect(predicate([1.1334], [1.1234], 2)).toBe(false);
+  });
+
+  test('returns false when floats differ by single digit due to rounding', () => {
+    expect(predicate([1.0001], [1.00015])).toBe(false);
+  });
+});

types/index.d.ts

@@ -52,6 +52,13 @@ declare namespace jest {
      */
     toBeArrayOfSize(x: number): R;
 
+    /**
+     * Use `.toBeArrayWithFloats` when checking if a value is an `Array` with floating-point numbers. Equality is checked using default or specified precision.
+     * @param {Array.<Number>} expected
+     * @param {Number} precision, i.e. decimal places taken into account during number comparison (1.0001 is not 1.00016, but 1.0001 is 1.00015 for precision = 4)
+     */
+    toBeArrayWithFloats(expected: number[], precision: number = 4): R;
+
     /**
      * Use `.toBeAfter` when checking if a date occurs after `date`.
      * @param {Date} date