resolves #6

compare-strings.js

@@ -8,6 +8,20 @@ exports.compareTwoStrings = compareTwoStrings;
 exports.findBestMatch = findBestMatch;
 
 function compareTwoStrings(str1, str2) {
+  var result = null;
+  result = calculateResultIfIdentical(str1, str2);
+  if (result != null) {
+    return result;
+  }
+  result = calculateResultIfEitherIsEmpty(str1, str2);
+  if (result != null) {
+    return result;
+  }
+  result = calculateResultIfBothAreSingleCharacter(str1, str2);
+  if (result != null) {
+    return result;
+  }
+
   var pairs1 = wordLetterPairs(str1.toUpperCase());
   var pairs2 = wordLetterPairs(str2.toUpperCase());
   var intersection = 0;
@@ -39,6 +53,39 @@ function compareTwoStrings(str1, str2) {
   function wordLetterPairs(str) {
     return _flattenDeep(_map(str.split(' '), letterPairs));
   }
+
+  function isEdgeCaseWithOneOrZeroChars(str1, str2) {
+    if (str1.length == str2.length && str1.length == 1) {
+      return true;
+    }
+    return false;
+  }
+
+  function calculateResultIfIdentical(str1, str2) {
+    if (str1.toUpperCase() == str2.toUpperCase()) {
+      return 1;
+    }
+    return null;
+  }
+
+  function calculateResultIfBothAreSingleCharacter(str1, str2) {
+    if (str1.length == 1 && str2.length == 1) {
+      return 0;
+    }
+  }
+
+  function calculateResultIfEitherIsEmpty(str1, str2) {
+    // if both are empty strings
+    if (str1.length == 0 && str2.length == 0) {
+      return 1;
+    }
+
+    // if only one is empty string
+    if ((str1.length + str2.length) > 0 && (str1.length * str2.length) == 0) {
+      return 0;
+    }
+    return null;
+  }
 }
 
 

compare-strings.spec.js

@@ -7,32 +7,25 @@ describe('compareTwoStrings', function () {
     expect(typeof compareTwoStrings).toBe('function');
   });
 
-  it('returns 0 for totally different strings: french and quebec', function () {
-    expect(compareTwoStrings('french', 'quebec')).toEqual(0);
-  });
-
-  it('returns 1 for identical strings: france and france', function () {
-    expect(compareTwoStrings('france', 'france')).toEqual(1);
-  });
-
-  it('returns 1 for same but differently cased strings: fRaNce and france', function () {
-    expect(compareTwoStrings('fRaNce', 'france')).toEqual(1);
-  });
-
-  it('returns 0.8 for healed and sealed', function () {
-    expect(compareTwoStrings('healed', 'sealed')).toEqual(0.8);
-  });
-
-  it('returns 0.896551724137931 for "web applications" and "applications of the web"', function () {
-    expect(compareTwoStrings('web applications', 'applications of the web')).toEqual(0.896551724137931);
-  });
-
-  it('returns 0.9 for "this will have a typo somewhere" and "this will huve a typo somewhere"', function () {
-    expect(compareTwoStrings("this will have a typo somewhere", "this will huve a typo somewhere")).toEqual(0.9);
-  });
-
-  it('returns 0.8333333333333334 for "this has one extra word" and "this has one word"', function () {
-    expect(compareTwoStrings("this has one extra word", "this has one word")).toEqual(0.8333333333333334);
+  it('returns the correct value for different inputs:', function () {
+    const testData = [
+      {first: 'french', second: 'quebec', expected: 0},  
+      {first: 'france', second: 'france', expected: 1},
+      {first: 'fRaNce', second: 'france', expected: 1},
+      {first: 'healed', second: 'sealed', expected: 0.8},
+      {first: 'web applications', second: 'applications of the web', expected: 0.896551724137931},
+      {first: 'this will have a typo somewhere', second: 'this will huve a typo somewhere', expected: 0.9},
+      {first: 'this has one extra word', second: 'this has one word', expected: 0.8333333333333334},
+      {first: 'a', second: 'a', expected: 1},
+      {first: 'a', second: 'b', expected: 0},
+      {first: '', second: '', expected: 1},
+      {first: 'a', second: '', expected: 0},
+      {first: '', second: 'a', expected: 0}
+    ];   
+
+    testData.forEach(td => {
+      expect(compareTwoStrings(td.first, td.second)).toEqual(td.expected);
+    });
   });
 });