test(core/browser/platform): 26 extreme RED/GREEN TDD cycles and full regression hardening (3,235 PASS)

tests/Paca.Tests/Detection/UrlAndMediaDetectionExtremeRedTests.cs

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+using System;
+using System.Collections.Generic;
+using Paca.Core.Config;
+using Paca.Core.Detection;
+using Paca.Core.Security;
+using Xunit;
+
+namespace Paca.Tests.Detection;
+
+public class UrlAndMediaDetectionExtremeRedTests
+{
+    [Theory]
+    [InlineData(null)]
+    [InlineData("")]
+    [InlineData("   ")]
+    [InlineData("not a url")]
+    [InlineData("javascript:alert('pwn')")]
+    [InlineData("data:text/html,<script>alert(1)</script>")]
+    [InlineData("file:///C:/Windows/System32/calc.exe")]
+    [InlineData("blob:https://youtube.com/1234-5678")]
+    public void SocialSiteDetector_TryMatchString_InvalidOrDangerousUrls_ReturnsFalse(string? input)
+    {
+        var result = SocialSiteDetector.TryMatch(input, out var normalized, out var label);
+        Assert.False(result);
+        Assert.Empty(normalized);
+        Assert.Empty(label);
+    }
+
+    [Theory]
+    [InlineData("https://www.youtube.com/watch?v=dQw4w9WgXcQ", "https://www.youtube.com/watch?v=dQw4w9WgXcQ", "YOUTUBE")]
+    [InlineData("https://youtu.be/dQw4w9WgXcQ", "https://www.youtube.com/watch?v=dQw4w9WgXcQ", "YOUTUBE")]
+    [InlineData("https://www.youtube.com/shorts/dQw4w9WgXcQ", "https://www.youtube.com/watch?v=dQw4w9WgXcQ", "YOUTUBE")]
+    [InlineData("https://twitter.com/OpenAI/status/1234567890", "https://x.com/OpenAI/status/1234567890", "X")]
+    [InlineData("https://x.com/OpenAI/status/1234567890", "https://x.com/OpenAI/status/1234567890", "X")]
+    [InlineData("https://www.instagram.com/reel/C_xyz123/", "https://www.instagram.com/reel/C_xyz123", "INSTAGRAM")]
+    [InlineData("https://www.tiktok.com/@user/video/1234567890", "https://www.tiktok.com/@user/video/1234567890", "TIKTOK")]
+    public void SocialSiteDetector_TryMatchString_ValidUrls_NormalizesCorrectly(string input, string expectedUrl, string expectedLabel)
+    {
+        var result = SocialSiteDetector.TryMatch(input, out var normalized, out var label);
+        Assert.True(result);
+        Assert.Equal(expectedUrl, normalized);
+        Assert.Equal(expectedLabel, label);
+    }
+
+    [Fact]
+    public void MediaDetector_Classify_NullConfig_ReturnsNullWithoutThrowing()
+    {
+        var result = MediaDetector.Classify("https://cdn.example.com/video.mp4", "video/mp4", 1024 * 1024, null!);
+        Assert.Null(result);
+    }
+
+    [Theory]
+    [InlineData("javascript:alert('xss')")]
+    [InlineData("data:video/mp4;base64,AAAA")]
+    [InlineData("file:///C:/videos/test.mp4")]
+    [InlineData("blob:https://example.com/uuid-1234")]
+    public void MediaDetector_Classify_DangerousSchemes_ReturnsNull(string dangerousUri)
+    {
+        var config = new AppConfig();
+        var result = MediaDetector.Classify(dangerousUri, "video/mp4", 1024 * 1024, config);
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public void MediaDetector_Classify_InvalidNegativeLengthBelowMinusOne_ReturnsNull()
+    {
+        var config = new AppConfig();
+        var result = MediaDetector.Classify("https://cdn.example.com/video.mp4", "video/mp4", -99999L, config);
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public void MediaDetector_ProbeFormat_BoundaryFtypBox_RecognizesMp4()
+    {
+        var ftypBytes = new byte[] { 0, 0, 0, 0x18, (byte)'f', (byte)'t', (byte)'y', (byte)'p', (byte)'m', (byte)'p', (byte)'4', (byte)'2' };
+        var format = MediaDetector.ProbeFormat(ftypBytes);
+        Assert.Equal("mp4", format);
+    }
+
+    [Fact]
+    public void CredentialSecurityAuditor_PerformAudit_NullList_ReturnsHealthyZeroReport()
+    {
+        var report = CredentialSecurityAuditor.PerformAudit(null!);
+        Assert.NotNull(report);
+        Assert.Equal(100, report.OverallHealthScore);
+        Assert.Equal(0, report.TotalAccounts);
+        Assert.Empty(report.Issues);
+    }
+
+    [Fact]
+    public void CredentialSecurityAuditor_PerformAudit_ListWithNullElements_FiltersNullsWithoutThrowing()
+    {
+        var credentials = new List<SiteCredentialRecord?>
+        {
+            new() { Id = "1", Domain = "example.com", Username = "user1", DecryptedPassword = "Password123!" },
+            null,
+            new() { Id = "2", Domain = "test.com", Username = "user2", DecryptedPassword = "SuperSecurePassword2026!#" }
+        };
+
+        var report = CredentialSecurityAuditor.PerformAudit(credentials!);
+        Assert.NotNull(report);
+        Assert.Equal(2, report.TotalAccounts);
+    }
+
+    [Fact]
+    public void CredentialSecurityAuditor_PerformAudit_DetectsWeakAndReusedPasswords()
+    {
+        var credentials = new List<SiteCredentialRecord>
+        {
+            new() { Id = "1", Domain = "site1.com", Username = "user", DecryptedPassword = "123" },
+            new() { Id = "2", Domain = "site2.com", Username = "user", DecryptedPassword = "123" }
+        };
+
+        var report = CredentialSecurityAuditor.PerformAudit(credentials);
+        Assert.True(report.WeakPasswordCount > 0);
+        Assert.True(report.ReusedPasswordCount > 0);
+        Assert.True(report.OverallHealthScore < 100);
+    }
+}