Confirm commit summary truncates with CLI git

JENKINS-29977 reports that command line git truncates on the first
word boundary preceding character 73 in the commit summary.

JGit does not truncate.

This test is intended to confirm that the existing behavior is
retained.  New optional behavior is being prepared based on a global
switch that will disable truncation of long commit summaries.

Author: MarkEWaite

src/test/java/hudson/plugins/git/GitChangeSetTruncateTest.java

@@ -0,0 +1,153 @@
+package hudson.plugins.git;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.io.UnsupportedEncodingException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Random;
+import java.util.UUID;
+
+import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.lib.ObjectId;
+
+import hudson.EnvVars;
+import hudson.model.TaskListener;
+import org.jenkinsci.plugins.gitclient.Git;
+import org.jenkinsci.plugins.gitclient.GitClient;
+
+import static org.hamcrest.Matchers.*;
+import static org.junit.Assert.*;
+import org.junit.BeforeClass;
+import org.junit.ClassRule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.jvnet.hudson.test.Issue;
+
+@RunWith(Parameterized.class)
+public class GitChangeSetTruncateTest {
+
+    @ClassRule
+    public static TemporaryFolder tempFolder = new TemporaryFolder();
+
+    private static File repoRoot = null;
+
+    private static final Random random = new Random();
+
+    /* Arguments to the constructor */
+    private final String gitImpl;
+    private final String commitSummary;
+    private final String expectedSummary;
+
+    /* Computed in the constructor, used in tests */
+    private final GitChangeSet changeSet;
+
+    private static class TestData {
+
+        final public String testDataCommitSummary;
+        final public String testDataExpectedSummary;
+
+        TestData(String commitSummary, String expectedSummary) {
+            this.testDataCommitSummary = commitSummary;
+            this.testDataExpectedSummary = expectedSummary;
+        }
+    }
+
+    //                                                    1         2         3         4         5         6         7
+    //                                           1234567890123456789012345678901234567890123456789012345678901234567890
+    private final static String SEVENTY_CHARS = "[JENKINS-012345] 8901 34567 90 23456 8901 34567 9012 4567890 2345678 0";
+    private final static String EIGHTY_CHARS  = "12345678901234567890123456789012345678901234567890123456789012345678901234567890";
+
+    private final static TestData[] TEST_DATA = {
+        new TestData(EIGHTY_CHARS,                         EIGHTY_CHARS), // surprising that longer than 72 is returned
+        new TestData(SEVENTY_CHARS,                        SEVENTY_CHARS),
+        new TestData(SEVENTY_CHARS + " 2",                 SEVENTY_CHARS + " 2"),
+        new TestData(SEVENTY_CHARS + " 2 4",               SEVENTY_CHARS + " 2"),
+        new TestData(SEVENTY_CHARS + " 23",                SEVENTY_CHARS),
+        new TestData(SEVENTY_CHARS + " 2&4",               SEVENTY_CHARS),
+        new TestData(SEVENTY_CHARS + "1",                  SEVENTY_CHARS + "1"),
+        new TestData(SEVENTY_CHARS + "1 3",                SEVENTY_CHARS + "1"),
+        new TestData(SEVENTY_CHARS + "1 <4",               SEVENTY_CHARS + "1"),
+        new TestData(SEVENTY_CHARS + "1 3 5",              SEVENTY_CHARS + "1"),
+        new TestData(SEVENTY_CHARS + "1;",                 SEVENTY_CHARS + "1;"),
+        new TestData(SEVENTY_CHARS + "1; 4",               SEVENTY_CHARS + "1;"),
+        new TestData(SEVENTY_CHARS + " " + SEVENTY_CHARS,  SEVENTY_CHARS),
+        new TestData(SEVENTY_CHARS + "  " + SEVENTY_CHARS, SEVENTY_CHARS + " ") // surprising that trailing space is preserved
+    };
+
+    public GitChangeSetTruncateTest(String gitImpl, String commitSummary, String expectedSummary) throws Exception {
+        this.gitImpl = gitImpl;
+        this.commitSummary = commitSummary;
+        this.expectedSummary = expectedSummary;
+        GitClient gitClient = Git.with(TaskListener.NULL, new EnvVars()).in(repoRoot).using(gitImpl).getClient();
+        final ObjectId head = commitOneFile(gitClient, commitSummary);
+        StringWriter changelogStringWriter = new StringWriter();
+        gitClient.changelog().includes(head).to(changelogStringWriter).execute();
+        List<String> changeLogList = Arrays.asList(changelogStringWriter.toString().split("\n"));
+        changeSet = new GitChangeSet(changeLogList, random.nextBoolean());
+    }
+
+    @Parameterized.Parameters(name = "{0} \"{1}\" --->>> \"{2}\"")
+    public static Collection gitObjects() {
+        String[] implementations = {"git", "jgit"};
+        List<Object[]> arguments = new ArrayList<>();
+        for (String implementation : implementations) {
+            for (TestData sample : TEST_DATA) {
+                /* Expect truncated message from git, full message from JGit */
+                String expected = implementation.equals("git") ? sample.testDataExpectedSummary : sample.testDataCommitSummary;
+                Object[] item = {implementation, sample.testDataCommitSummary, expected};
+                arguments.add(item);
+            }
+        }
+        Collections.shuffle(arguments); // Execute in random order
+        return arguments;
+    }
+
+    @BeforeClass
+    public static void createRepo() throws Exception {
+        repoRoot = tempFolder.newFolder();
+        String initialImpl = random.nextBoolean() ? "git" : "jgit";
+        GitClient gitClient = Git.with(TaskListener.NULL, new EnvVars()).in(repoRoot).using(initialImpl).getClient();
+        gitClient.init_().workspace(repoRoot.getAbsolutePath()).execute();
+    }
+
+    private ObjectId commitOneFile(GitClient gitClient, final String commitSummary) throws Exception {
+        String path = "One-File.txt";
+        String content = String.format("A random UUID: %s\n", UUID.randomUUID().toString());
+        /* randomize whether commit message is single line or multi-line */
+        String commitMessageBody = random.nextBoolean() ? "\n\n" + "committing " + path + " with content:\n\n" + content : "";
+        String commitMessage = commitSummary + commitMessageBody;
+        createFile(path, content);
+        gitClient.add(path);
+        gitClient.commit(commitMessage);
+        List<ObjectId> headList = gitClient.revList(Constants.HEAD);
+        assertThat(headList.size(), is(greaterThan(0)));
+        return headList.get(0);
+    }
+
+    private void createFile(String path, String content) throws Exception {
+        File aFile = new File(repoRoot, path);
+        File parentDir = aFile.getParentFile();
+        if (parentDir != null) {
+            parentDir.mkdirs();
+        }
+        try (PrintWriter writer = new PrintWriter(aFile, "UTF-8")) {
+            writer.printf(content);
+        } catch (FileNotFoundException | UnsupportedEncodingException ex) {
+            throw new GitException(ex);
+        }
+    }
+
+    @Test
+    @Issue("JENKINS-29977") // CLI git truncates first line of commit message in Changes page
+    public void summaryTruncatedAtLastWord72CharactersOrLess() throws Exception {
+        assertThat(changeSet.getMsg(), is(expectedSummary));
+    }
+}