Improve 'compilation required' check by checking source file dependencies

src/WebCompiler/Config/Config.cs

@@ -1,5 +1,6 @@
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using Newtonsoft.Json;
 
 namespace WebCompiler
@@ -74,15 +75,54 @@ public FileInfo GetAbsoluteOutputFile()
         /// <summary>
         /// Checks to see if the input file needs compilation
         /// </summary>
-        internal bool CompilationRequired()
+        public bool CompilationRequired()
         {
             FileInfo input = GetAbsoluteInputFile();
             FileInfo output = GetAbsoluteOutputFile();
 
             if (!output.Exists)
                 return true;
 
-            return input.LastWriteTimeUtc > output.LastWriteTimeUtc;
+            if (input.LastWriteTimeUtc > output.LastWriteTimeUtc)
+                return true;
+
+            return HasDependenciesNewerThanOutput(input, output);
+        }
+
+        private bool HasDependenciesNewerThanOutput(FileInfo input, FileInfo output)
+        {
+            var projectRoot = new FileInfo(FileName).DirectoryName;
+            var dependencies = DependencyService.GetDependencies(projectRoot, input.FullName);
+
+            if (dependencies != null)
+            {
+                string key = input.FullName.ToLowerInvariant();
+                return CheckForNewerDependenciesRecursively(key, dependencies, output);
+            }
+
+            return false;
+        }
+
+        private bool CheckForNewerDependenciesRecursively(string key, Dictionary<string, Dependencies> dependencies, FileInfo output)
+        {
+            if (!dependencies.ContainsKey(key))
+                return false;
+
+            foreach (var file in dependencies[key].DependentOn.ToArray())
+            {
+                var fileInfo = new FileInfo(file);
+
+                if (!fileInfo.Exists)
+                    continue;
+
+                if (fileInfo.LastWriteTimeUtc > output.LastWriteTimeUtc)
+                    return true;
+
+                if (CheckForNewerDependenciesRecursively(file, dependencies, output))
+                    return true;
+            }
+
+            return false;
         }
 
         /// <summary>

src/WebCompilerTest/Config/ConfigTest.cs

@@ -0,0 +1,120 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace WebCompilerTest.Config
+{
+    [TestClass]
+    public class ConfigTest
+    {
+        private WebCompiler.Config _config;
+
+        private const string dummyConfigFile = "../../artifacts/config/dummy.json";
+        private const string inputFile = "../../artifacts/config/compilationrequired.scss";
+        private const string outputFile = "../../artifacts/config/compilationrequired.css";
+        private const string firstLevelDependencyFile = "../../artifacts/config/dependencies/foo.scss";
+        private const string secondLevelDependencyFile = "../../artifacts/config/dependencies/sub/bar.scss";
+
+        private readonly FileInfo _inputFileInfo = new FileInfo(inputFile);
+        private readonly FileInfo _outputFileInfo = new FileInfo(outputFile);
+        private readonly FileInfo _firstLevelDependencyFileInfo = new FileInfo(firstLevelDependencyFile);
+        private readonly FileInfo _secondLevelDependencyFileInfo = new FileInfo(secondLevelDependencyFile);
+
+        private readonly Dictionary<FileInfo, DateTime> _originalLastWriteTimes = new Dictionary<FileInfo, DateTime>();
+
+        private DateTime _olderWriteTime;
+        private DateTime _newerWriteTime;
+
+        [TestInitialize]
+        public void Setup()
+        {
+            var configFileInfo = new FileInfo(dummyConfigFile);
+
+            _config = new WebCompiler.Config
+            {
+                FileName = configFileInfo.FullName,
+                InputFile = _inputFileInfo.FullName,
+                OutputFile = _outputFileInfo.FullName
+            };
+
+            // Create dummy output file, only last write time is checked
+            File.WriteAllText(outputFile, "");
+
+            // Backup last write times for cleanup
+            _originalLastWriteTimes.Add(_inputFileInfo, _inputFileInfo.LastWriteTimeUtc);
+            _originalLastWriteTimes.Add(_firstLevelDependencyFileInfo, _firstLevelDependencyFileInfo.LastWriteTimeUtc);
+            _originalLastWriteTimes.Add(_secondLevelDependencyFileInfo, _secondLevelDependencyFileInfo.LastWriteTimeUtc);
+
+            var utcNow = DateTime.UtcNow;
+
+            _inputFileInfo.LastWriteTimeUtc = utcNow;
+            _outputFileInfo.LastWriteTimeUtc = utcNow;
+            _firstLevelDependencyFileInfo.LastWriteTimeUtc = utcNow;
+            _secondLevelDependencyFileInfo.LastWriteTimeUtc = utcNow;
+
+            _olderWriteTime = utcNow.AddHours(-1);
+            _newerWriteTime = utcNow.AddHours(1);
+        }
+
+        [TestCleanup]
+        public void Cleanup()
+        {
+            if (File.Exists(outputFile))
+                File.Delete(outputFile);
+
+            foreach (var entry in _originalLastWriteTimes)
+            {
+                entry.Key.LastWriteTimeUtc = entry.Value;
+            }
+        }
+
+        [TestMethod, TestCategory("Config")]
+        public void CompilationRequired_OutputNewerThanEverything_DoesNotRequireCompilation()
+        {
+            _inputFileInfo.LastWriteTimeUtc = _olderWriteTime;
+            _firstLevelDependencyFileInfo.LastWriteTimeUtc = _olderWriteTime;
+            _secondLevelDependencyFileInfo.LastWriteTimeUtc = _olderWriteTime;
+
+            var compilationRequired = _config.CompilationRequired();
+
+            Assert.AreEqual(false, compilationRequired);
+        }
+
+        [TestMethod, TestCategory("Config")]
+        public void CompilationRequired_InputNewerThanOutput_RequiresCompilation()
+        {
+            _inputFileInfo.LastWriteTimeUtc = _newerWriteTime;
+            _firstLevelDependencyFileInfo.LastWriteTimeUtc = _olderWriteTime;
+            _secondLevelDependencyFileInfo.LastWriteTimeUtc = _olderWriteTime;
+
+            var compilationRequired = _config.CompilationRequired();
+
+            Assert.AreEqual(true, compilationRequired);
+        }
+
+        [TestMethod, TestCategory("Config")]
+        public void CompilationRequired_FirstLevelDependencyNewerThanOutput_RequiresCompilation()
+        {
+            _inputFileInfo.LastWriteTimeUtc = _olderWriteTime;
+            _firstLevelDependencyFileInfo.LastWriteTimeUtc = _newerWriteTime;
+            _secondLevelDependencyFileInfo.LastWriteTimeUtc = _olderWriteTime;
+
+            var compilationRequired = _config.CompilationRequired();
+
+            Assert.AreEqual(true, compilationRequired);
+        }
+
+        [TestMethod, TestCategory("Config")]
+        public void CompilationRequired_SecondLevelDependencyNewerThanOutput_RequiresCompilation()
+        {
+            _inputFileInfo.LastWriteTimeUtc = _olderWriteTime;
+            _firstLevelDependencyFileInfo.LastWriteTimeUtc = _olderWriteTime;
+            _secondLevelDependencyFileInfo.LastWriteTimeUtc = _newerWriteTime;
+
+            var compilationRequired = _config.CompilationRequired();
+
+            Assert.AreEqual(true, compilationRequired);
+        }
+    }
+}

src/WebCompilerTest/WebCompilerTest.csproj

@@ -66,6 +66,7 @@
     <Compile Include="Compile\ScssOptionsTest.cs" />
     <Compile Include="Compile\ScssTest.cs" />
     <Compile Include="Compile\LessTest.cs" />
+    <Compile Include="Config\ConfigTest.cs" />
     <Compile Include="Minify\JavaScriptOptionsTests.cs" />
     <Compile Include="Minify\CssOptionsTests.cs" />
     <Compile Include="Minify\CssMinifierTests.cs" />
@@ -74,6 +75,9 @@
   </ItemGroup>
   <ItemGroup>
     <Content Include="artifacts\less\sub\logo.png" />
+    <None Include="artifacts\config\compilationrequired.scss" />
+    <None Include="artifacts\config\dependencies\sub\bar.scss" />
+    <None Include="artifacts\config\dependencies\foo.scss" />
     <None Include="artifacts\handlebarsconfigPartial.json" />
     <None Include="artifacts\handlebarsconfig.json" />
     <None Include="artifacts\coffeeconfig.json.defaults" />

src/WebCompilerTest/artifacts/config/compilationrequired.scss

@@ -0,0 +1 @@
+@import "dependencies/foo";

src/WebCompilerTest/artifacts/config/dependencies/foo.scss

@@ -0,0 +1 @@
+@import "sub/bar";

src/WebCompilerTest/artifacts/config/dependencies/sub/bar.scss

@@ -0,0 +1 @@
+