bubble sort algorithm

src/sort/bubble.js

@@ -1,3 +1,34 @@
-module.exports = function (arr, comp) {
-  console.log('ok')
-}
+function normalCompare(prev, next) {
+  if (prev < next) {
+    return -1;
+  } else if (prev == next) {
+    return 0;
+  } else {
+    return 1;
+  }
+}
+/**
+ * explaining here: https://visualgo.net/en/sorting?slide=5
+ * 
+ * @param {Array} src - source data, it should be an Array
+ * @return {Array}
+ */
+function sort (src, comp = normalCompare) {
+  if (! (src instanceof Array)) {
+    throw new Error('expect param 1 to be an Array')
+  }
+  let result = [].concat(src);
+
+  for (let i = 0, len = result.length; i < len - 1; i++) {
+    for (let j = 0; j < len - 1 - i; j++) {
+      // if prev value greater than next value, just exchange them
+      if (comp(result[j], result[j + 1]) === 1) {
+        let temp = result[j];
+        result[j] = result[j + 1];
+        result[j + 1] = temp;
+      }
+    }
+  }
+  return result;
+}
+module.exports = sort;

test/sort/bubble.spec.js

@@ -1,3 +1,71 @@
-describe('> bubble sort', () => {
-  it('ok', () => {})
+const sort = require('../../src/sort/bubble');
+const expect = require('chai').expect
+
+describe('> bubble sort algorithm', () => {
+  describe('> Wrong Usage', () => {
+    it('wrong parameter', () => {
+      try {
+        sort(5)
+      } catch(e) {
+        expect(e.message).to.equal('expect param 1 to be an Array');
+      }
+    });
+  });
+
+  it('sort number', () => {
+    let arr = [5, 4, 3, 1, 2];
+    let result = sort(arr);
+    expect(result).to.deep.equal(
+      [1, 2, 3, 4, 5]
+    );
+
+    arr = [-4, -4, -2, -2, 4, 3, 1, 2];
+    result = sort(arr);
+    expect(result).to.deep.equal(
+      [-4, -4, -2, -2, 1, 2, 3, 4]
+    );
+  });
+
+  it('sort letter', () => {
+    let arr = ['a', 'c', 'd', 'b', 'e'];
+    let result = sort(arr);
+    expect(result).to.deep.equal(
+      ['a', 'b', 'c', 'd', 'e']
+    );
+  });
+
+  it('custom comparator', () => {
+    let arr = [
+      {
+        value: 6,
+      },
+      {
+        value: 3,
+      },
+      {
+        value: 1,
+      },
+      {
+        value: 4,
+      }
+    ];
+    let result = sort(arr, (prev, next) => {
+      if (prev.value > next.value) return 1;
+      return -1;
+    });
+    expect(result).to.deep.equal([
+      {
+        value: 1,
+      },
+      {
+        value: 3,
+      },
+      {
+        value: 4,
+      },
+      {
+        value: 6,
+      }
+    ]);
+  });
 });