[Hacker Rank] Interview Preparation Kit: Dictionaries and Hashmaps: Frequency Queries. Coverage increased.

Author: Gonzalo Diaz

algorithm-exercises-java/src/main/java/ae/hackerrank/interview_preparation_kit/dictionaries_and_hashmaps/FrequencyQueries.java

@@ -96,7 +96,8 @@ static List<Integer> freqQuery(List<List<Integer>> queries) {
           result.add(freqMap.containsKey(value) ? __FOUND__ : __NOT_FOUND__);
           break;
         default:
-          break;
+          throw new IllegalArgumentException(
+              "Operation %d not supported".formatted(operation));
       }
     }
 

algorithm-exercises-java/src/test/java/ae/hackerrank/interview_preparation_kit/dictionaries_and_hashmaps/FrequencyQueriesTest.java

@@ -1,6 +1,8 @@
 package ae.hackerrank.interview_preparation_kit.dictionaries_and_hashmaps;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.io.IOException;
 import java.util.List;
@@ -21,6 +23,8 @@ public static class FrequencyQueriesTestCase {
 
   List<FrequencyQueriesTestCase> testCases;
   List<FrequencyQueriesTestCase> testCase6;
+  List<FrequencyQueriesTestCase> testCaseBorderCases;
+  List<FrequencyQueriesTestCase> testCaseBorderCaseException;
 
   @BeforeAll
   public void setup() throws IOException {
@@ -39,6 +43,20 @@ public void setup() throws IOException {
         "dictionaries_and_hashmaps",
         "frequency_queries.testcase6.json");
     this.testCase6 = JsonLoader.loadJson(path, FrequencyQueriesTestCase.class);
+
+    path = String.join("/",
+      "hackerrank",
+      "interview_preparation_kit",
+      "dictionaries_and_hashmaps",
+      "frequency_queries.testcase_border_cases.json");
+    this.testCaseBorderCases = JsonLoader.loadJson(path, FrequencyQueriesTestCase.class);
+
+    path = String.join("/",
+      "hackerrank",
+      "interview_preparation_kit",
+      "dictionaries_and_hashmaps",
+      "frequency_queries.testcase_border_case_exception.json");
+    this.testCaseBorderCaseException = JsonLoader.loadJson(path, FrequencyQueriesTestCase.class);
   }
 
   @Test
@@ -71,4 +89,34 @@ void testFrequencyQueriesBigCases() {
               test.expected));
     }
   }
+
+  @Test
+  void testFrequencyQueriesBorderCases() {
+    List<Integer> solutionFound;
+
+    for (FrequencyQueriesTestCase test : testCaseBorderCases) {
+
+      solutionFound = FrequencyQueries.freqQuery(test.input);
+
+      assertEquals(test.expected, solutionFound,
+          "%s(%s) answer must be: %s".formatted(
+              "FrequencyQueriesTest.freqQuery",
+              test.input,
+              test.expected));
+    }
+  }
+
+  @Test
+  void testFrequencyQueriesBorderCaseException() {
+    for (FrequencyQueriesTestCase test : testCaseBorderCaseException) {
+      Exception exception = assertThrows(IllegalArgumentException.class, () -> {
+        FrequencyQueries.freqQuery(test.input);
+      });
+
+      String expectedMessage = "Operation 4 not supported";
+      String actualMessage = exception.getMessage();
+
+      assertTrue(actualMessage.contains(expectedMessage));
+    }
+  }
 }

algorithm-exercises-java/src/test/resources/hackerrank/interview_preparation_kit/dictionaries_and_hashmaps/frequency_queries.testcase_border_case_exception.json

@@ -0,0 +1,9 @@
+[
+  {
+    "title": "Test Case Border Case when operation doesn't exists",
+    "input": [
+      [4, 1]
+    ],
+    "expected": []
+  }
+]

algorithm-exercises-java/src/test/resources/hackerrank/interview_preparation_kit/dictionaries_and_hashmaps/frequency_queries.testcase_border_cases.json

@@ -0,0 +1,19 @@
+[
+  {
+    "title": "Test Case Border Case when decrease in frequency already exists",
+    "input": [
+      [1, 1],
+      [1, 1],
+      [1, 1],
+      [2, 1],
+      [1, 2],
+      [1, 2],
+      [1, 2],
+      [2, 2],
+      [3, 1],
+      [3, 2],
+      [3, 3]
+    ],
+    "expected": [0, 1, 0]
+  }
+]