diff --git a/tests/test_confidence.py b/tests/test_confidence.py
new file mode 100644
index 0000000..8bb8398
--- /dev/null
+++ b/tests/test_confidence.py
@@ -0,0 +1,287 @@
+"""Tests for confidence scoring module."""
+
+import pytest
+
+from src.core.models import ScanResult, Issue, IssueCategory, SeverityLevel
+from src.reporting.confidence import ConfidenceScorer
+
+
+class TestConfidenceScorer:
+    """Tests for ConfidenceScorer."""
+
+    def test_calculate_perfect_score(self, clean_python_code):
+        """Test that clean code gets a high score."""
+        scorer = ConfidenceScorer()
+        result = ScanResult(files_scanned=1, target_path="/test")
+        score = scorer.calculate(result)
+        assert score == 100
+
+    def test_calculate_with_issues(self, mock_scan_result):
+        """Test score calculation with issues."""
+        scorer = ConfidenceScorer()
+        score = scorer.calculate(mock_scan_result)
+        assert score < 100
+        assert score >= 0
+
+    def test_security_issues_reduce_score_more(self):
+        """Test that security issues reduce score more than other issues."""
+        scorer = ConfidenceScorer()
+
+        result_security = ScanResult(files_scanned=1, target_path="/test")
+        result_security.add_issue(Issue(
+            severity=SeverityLevel.HIGH,
+            category=IssueCategory.SECURITY,
+            file_path="/test.py",
+            line_number=1,
+            message="Security issue",
+            scanner_name="test",
+        ))
+
+        result_quality = ScanResult(files_scanned=1, target_path="/test")
+        result_quality.add_issue(Issue(
+            severity=SeverityLevel.HIGH,
+            category=IssueCategory.CODE_QUALITY,
+            file_path="/test.py",
+            line_number=1,
+            message="Quality issue",
+            scanner_name="test",
+        ))
+
+        security_score = scorer.calculate(result_security)
+        quality_score = scorer.calculate(result_quality)
+
+        assert security_score < quality_score
+
+    def test_critical_issues_reduce_score_more(self):
+        """Test that critical issues reduce score more."""
+        scorer = ConfidenceScorer()
+
+        result_critical = ScanResult(files_scanned=1, target_path="/test")
+        result_critical.add_issue(Issue(
+            severity=SeverityLevel.CRITICAL,
+            category=IssueCategory.SECURITY,
+            file_path="/test.py",
+            line_number=1,
+            message="Critical issue",
+            scanner_name="test",
+        ))
+
+        result_high = ScanResult(files_scanned=1, target_path="/test")
+        result_high.add_issue(Issue(
+            severity=SeverityLevel.HIGH,
+            category=IssueCategory.SECURITY,
+            file_path="/test.py",
+            line_number=1,
+            message="High issue",
+            scanner_name="test",
+        ))
+
+        critical_score = scorer.calculate(result_critical)
+        high_score = scorer.calculate(result_high)
+
+        assert critical_score < high_score
+
+    def test_get_score_breakdown(self, mock_scan_result):
+        """Test score breakdown generation."""
+        scorer = ConfidenceScorer()
+        breakdown = scorer.get_score_breakdown(mock_scan_result)
+
+        assert "base_score" in breakdown
+        assert "total_deductions" in breakdown
+        assert "final_score" in breakdown
+        assert "issues_by_category" in breakdown
+        assert "issues_by_severity" in breakdown
+
+    def test_get_score_grade(self):
+        """Test score grade calculation."""
+        scorer = ConfidenceScorer()
+
+        assert scorer.get_score_grade(95) == "A+"
+        assert scorer.get_score_grade(90) == "A"
+        assert scorer.get_score_grade(85) == "A-"
+        assert scorer.get_score_grade(80) == "B+"
+        assert scorer.get_score_grade(75) == "B"
+        assert scorer.get_score_grade(70) == "B-"
+        assert scorer.get_score_grade(65) == "C+"
+        assert scorer.get_score_grade(60) == "C"
+        assert scorer.get_score_grade(55) == "C-"
+        assert scorer.get_score_grade(50) == "D+"
+        assert scorer.get_score_grade(45) == "D"
+        assert scorer.get_score_grade(40) == "D-"
+        assert scorer.get_score_grade(30) == "F"
+
+    def test_get_score_description(self):
+        """Test score description generation."""
+        scorer = ConfidenceScorer()
+
+        desc_90 = scorer.get_score_description(90)
+        assert "Excellent" in desc_90
+
+        desc_75 = scorer.get_score_description(75)
+        assert "Good" in desc_75
+
+        desc_50 = scorer.get_score_description(50)
+        assert "Poor" in desc_50
+
+        desc_25 = scorer.get_score_description(25)
+        assert "Critical" in desc_25
+
+    def test_empty_result_gets_100(self):
+        """Test that empty scan result gets 100 score."""
+        scorer = ConfidenceScorer()
+        result = ScanResult(files_scanned=0, target_path="/test")
+        score = scorer.calculate(result)
+        assert score == 100
+
+    def test_score_never_negative(self):
+        """Test that score never goes below 0."""
+        scorer = ConfidenceScorer()
+
+        result = ScanResult(files_scanned=1, target_path="/test")
+        for _ in range(100):
+            result.add_issue(Issue(
+                severity=SeverityLevel.CRITICAL,
+                category=IssueCategory.SECURITY,
+                file_path="/test.py",
+                line_number=1,
+                message="Critical issue",
+                scanner_name="test",
+            ))
+
+        score = scorer.calculate(result)
+        assert score >= 0
+
+    def test_score_never_exceeds_100(self):
+        """Test that score never goes above 100."""
+        scorer = ConfidenceScorer()
+        result = ScanResult(files_scanned=10, target_path="/test")
+        score = scorer.calculate(result)
+        assert score <= 100
+
+
+class TestIssueModel:
+    """Tests for Issue data model."""
+
+    def test_issue_to_dict(self):
+        """Test issue serialization to dictionary."""
+        issue = Issue(
+            severity=SeverityLevel.HIGH,
+            category=IssueCategory.SECURITY,
+            file_path="/test.py",
+            line_number=10,
+            message="Test issue",
+            suggestion="Fix this",
+            scanner_name="test",
+        )
+
+        data = issue.to_dict()
+
+        assert data["severity"] == "high"
+        assert data["category"] == "security"
+        assert data["file_path"] == "/test.py"
+        assert data["line_number"] == 10
+        assert data["message"] == "Test issue"
+        assert data["suggestion"] == "Fix this"
+        assert data["scanner_name"] == "test"
+
+
+class TestScanResultModel:
+    """Tests for ScanResult data model."""
+
+    def test_add_issue(self):
+        """Test adding issues to scan result."""
+        result = ScanResult(files_scanned=1, target_path="/test")
+        issue = Issue(
+            severity=SeverityLevel.LOW,
+            category=IssueCategory.STYLE,
+            file_path="/test.py",
+            line_number=1,
+            message="Style issue",
+            scanner_name="test",
+        )
+
+        result.add_issue(issue)
+
+        assert len(result.issues) == 1
+        assert result.issues[0] == issue
+
+    def test_add_warning(self):
+        """Test adding warnings to scan result."""
+        result = ScanResult(files_scanned=1, target_path="/test")
+        result.add_warning("Test warning")
+
+        assert len(result.warnings) == 1
+        assert result.warnings[0] == "Test warning"
+
+    def test_filter_by_severity(self):
+        """Test filtering issues by severity."""
+        result = ScanResult(files_scanned=1, target_path="/test")
+        result.add_issue(Issue(
+            severity=SeverityLevel.LOW,
+            category=IssueCategory.STYLE,
+            file_path="/test.py",
+            line_number=1,
+            message="Low issue",
+            scanner_name="test",
+        ))
+        result.add_issue(Issue(
+            severity=SeverityLevel.CRITICAL,
+            category=IssueCategory.SECURITY,
+            file_path="/test.py",
+            line_number=2,
+            message="Critical issue",
+            scanner_name="test",
+        ))
+
+        filtered = result.filter_by_severity(SeverityLevel.HIGH)
+
+        assert len(filtered.issues) == 1
+        assert filtered.issues[0].severity == SeverityLevel.CRITICAL
+
+    def test_get_summary(self):
+        """Test getting scan summary."""
+        result = ScanResult(files_scanned=2, target_path="/test")
+        result.add_issue(Issue(
+            severity=SeverityLevel.HIGH,
+            category=IssueCategory.SECURITY,
+            file_path="/test.py",
+            line_number=1,
+            message="Issue 1",
+            scanner_name="test",
+        ))
+        result.add_issue(Issue(
+            severity=SeverityLevel.LOW,
+            category=IssueCategory.STYLE,
+            file_path="/test.py",
+            line_number=2,
+            message="Issue 2",
+            scanner_name="test",
+        ))
+
+        summary = result.get_summary()
+
+        assert summary["files_scanned"] == 2
+        assert summary["total_issues"] == 2
+        assert "high" in summary["issues_by_severity"]
+        assert "low" in summary["issues_by_severity"]
+        assert "security" in summary["issues_by_category"]
+        assert "style" in summary["issues_by_category"]
+
+    def test_to_dict(self):
+        """Test scan result serialization to dictionary."""
+        result = ScanResult(files_scanned=1, target_path="/test")
+        result.add_issue(Issue(
+            severity=SeverityLevel.MEDIUM,
+            category=IssueCategory.CODE_QUALITY,
+            file_path="/test.py",
+            line_number=5,
+            message="Test issue",
+            scanner_name="test",
+        ))
+
+        data = result.to_dict()
+
+        assert data["files_scanned"] == 1
+        assert data["target_path"] == "/test"
+        assert len(data["issues"]) == 1
+        assert data["issues"][0]["severity"] == "medium"