Merge pull request #64 from sillsdev/FileUpdate-should-not-fail-if-li…

…teral-replacementtext-is-found

FileUpdate: do not fail if literal ReplacementText is found

SIL.BuildTasks.Tests/FileUpdateTests.cs

@@ -21,6 +21,8 @@ public class FileUpdateTests
 			ExpectedResult = "There were approximately 35 frog princes.")]
 		[TestCase("There were 35 frog princes.", "(?<number>\\d+)", "approximately ${number}",
 			ExpectedResult = "There were approximately 35 frog princes.")]
+		[TestCase("</TargetFrameworkProfile>\r\n    <Version>0.0.0.0</Version> <!-- Replaced by FileUpdate in build/build.proj -->    <Authors>SIL</Authors>", "<Version>0\\.0\\.0\\.0</Version>", "<Version>3.3.0</Version>",
+			ExpectedResult = "</TargetFrameworkProfile>\r\n    <Version>3.3.0</Version> <!-- Replaced by FileUpdate in build/build.proj -->    <Authors>SIL</Authors>")]
 		public string GetModifiedContents_RegexTextMatched_Succeeds(string origContents, string regex, string replacement)
 		{
 			var updater = new FileUpdate
@@ -32,6 +34,18 @@ public string GetModifiedContents_RegexTextMatched_Succeeds(string origContents,
 			return updater.GetModifiedContents(origContents);
 		}
 
+		[TestCase("</TargetFrameworkProfile>\r\n    <Version>3.3.0</Version> <!-- Previously replaced by FileUpdate in build/build.proj -->    <Authors>SIL</Authors>", "<Version>0\\.0\\.0\\.0</Version>", "<Version>3.3.0</Version>")]
+		public void GetModifiedContents_RegexTextNotMatchedButReplacementTextFound_NoChangeOrError(string origContents, string regex, string replacement)
+		{
+			var updater = new FileUpdate
+			{
+				Regex = regex,
+				ReplacementText = replacement
+			};
+
+			Assert.That(updater.GetModifiedContents(origContents), NUnit.Framework.Is.EqualTo(origContents));
+		}
+
 		[TestCase("This is the story of the frog prince.", "princess", "soup")]
 		[TestCase("This is the story of the frog prince.", "\\d+", "14")]
 		public void GetModifiedContents_RegexTextNotMatched_Throws(string origContents, string regex, string replacement)

SIL.BuildTasks/FileUpdate.cs

@@ -60,7 +60,20 @@ internal string GetModifiedContents(string content)
 			{
 				var regex = new Regex(Regex);
 				if (!regex.IsMatch(content))
-					throw new Exception($"No replacements made. Regex: '{Regex}'; ReplacementText: '{ReplacementText}'");
+				{
+					// This check will generally only work if ReplacementText is just a literal string.
+					// If it contains references to regex match groups, and GetModifiedContents is run
+					// against a previously modified file with the same arguments, most likely no match
+					// will be found, and the "No replacements made" error will be displayed.
+					if (content.Contains(ReplacementText))
+					{
+						// Most likely, the replacement was already done an a previous build step.
+						return content;
+					}
+
+					throw new Exception($"No replacements made. Regex: '{Regex}'; " +
+						$"ReplacementText: '{ReplacementText}'");
+				}
 
 				var newContents = regex.Replace(content, ReplacementText);