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Add unit tests for the "Search in a Binary Search Tree" problem. #45

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Merged
kobukuro merged 1 commit into from
Feb 20, 2026
Merged

Add unit tests for the "Search in a Binary Search Tree" problem. #45

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18 changes: 0 additions & 18 deletions src/SearchInaBinarySearchTree700.java
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24 changes: 24 additions & 0 deletions src/main/java/com/leetcode/easy/SearchInABinarySearchTree700.java
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Original file line number Diff line number Diff line change
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// Tags: Tree, DFS
package com.leetcode.easy;

import com.leetcode.datastructure.TreeNode;

public class SearchInABinarySearchTree700 {
/**
* Time complexity: O(H), where H is a tree height.
* That results in O(logN) in the average case, and O(N) in the worst case.
* <p>
* Space complexity: O(H) to keep the recursion stack,
* i.e. O(logN) in the average case, and O(N) in the worst case.
*/
public TreeNode searchBST(TreeNode root, int val) {
if (root == null || root.val == val) {
return root;
}
if (root.val > val) {
return this.searchBST(root.left, val);
} else {
return this.searchBST(root.right, val);
}
}
}
45 changes: 45 additions & 0 deletions src/test/java/com/leetcode/easy/SearchInABinarySearchTree700Test.java
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package com.leetcode.easy;

import com.leetcode.datastructure.TreeNode;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNull;

public class SearchInABinarySearchTree700Test {
private SearchInABinarySearchTree700 solution;

@BeforeEach
void setUp() {
solution = new SearchInABinarySearchTree700();
}

@Test
void testSearchBST_Example1() {
TreeNode root = new TreeNode(4);
root.left = new TreeNode(2);
root.right = new TreeNode(7);
root.left.left = new TreeNode(1);
root.left.right = new TreeNode(3);
int val = 2;

TreeNode result = solution.searchBST(root, val);

assertEquals(result, root.left);
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Copilot AI Feb 20, 2026

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The assertEquals parameters are in the wrong order. The convention in JUnit and throughout this codebase is assertEquals(expected, actual), but here it's assertEquals(actual, expected). This should be assertEquals(root.left, result) to match the pattern used in other tests.

Suggested change
assertEquals(result, root.left);
assertEquals(root.left, result);

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}

@Test
void testSearchBST_Example2() {
TreeNode root = new TreeNode(4);
root.left = new TreeNode(2);
root.right = new TreeNode(7);
root.left.left = new TreeNode(1);
root.left.right = new TreeNode(3);
int val = 5;

TreeNode result = solution.searchBST(root, val);

assertNull(result);
}
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Copilot AI Feb 20, 2026

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The test coverage is incomplete. Consider adding tests for important edge cases: 1) null root (should return null), 2) value found at root node (should return root), and 3) value found in right subtree (currently only left subtree is tested). These cases are handled in the implementation but not verified by tests.

Suggested change
}
}
@Test
void testSearchBST_NullRoot() {
TreeNode root = null;
int val = 1;
TreeNode result = solution.searchBST(root, val);
assertNull(result);
}
@Test
void testSearchBST_ValueAtRoot() {
TreeNode root = new TreeNode(4);
root.left = new TreeNode(2);
root.right = new TreeNode(7);
root.left.left = new TreeNode(1);
root.left.right = new TreeNode(3);
int val = 4;
TreeNode result = solution.searchBST(root, val);
assertEquals(root, result);
}
@Test
void testSearchBST_ValueInRightSubtree() {
TreeNode root = new TreeNode(4);
root.left = new TreeNode(2);
root.right = new TreeNode(7);
root.left.left = new TreeNode(1);
root.left.right = new TreeNode(3);
int val = 7;
TreeNode result = solution.searchBST(root, val);
assertEquals(root.right, result);
}

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}