[copybara] allow rfc 822 format in custom-rev-id

The current regex enforces a suffix `REV_ID` for custom-rev-id so it
can never meet RFC 822 format (no underscore) and does not work with
git trailer (https://git-scm.com/docs/git-interpret-trailers).

Loosen the restriction, and allow RFC 822 format.

Change-Id: If2e136f5e5f65164cd55c3144247704b42727f16

Author: whhone

java/com/google/copybara/Core.java

@@ -125,8 +125,12 @@
 @UsesFlags({GeneralOptions.class, DebugOptions.class})
 public class Core implements LabelsAwareModule, StarlarkValue {
 
-  // Restrict for label ids like 'BAZEL_REV_ID'. More strict than our current revId.
-  private static final Pattern CUSTOM_REVID_FORMAT = Pattern.compile("[A-Z][A-Z_0-9]{1,30}_REV_ID");
+  // Restrict for label ids like 'BAZEL_REV_ID' or 'Bazel-RevId'.
+  //
+  // It is suggested to meet the RFC 822 format (e.g., no underscore) so that it works with git
+  // trailer (https://git-scm.com/docs/git-interpret-trailers).
+  private static final Pattern CUSTOM_REVID_FORMAT =
+      Pattern.compile("([A-Z][A-Z_0-9]{1,30}_REV_ID|[A-Z][a-zA-Z0-9-]{1,30}-RevId)");
   private static final String CHECK_LAST_REV_STATE = "check_last_rev_state";
   private final GeneralOptions generalOptions;
   private final WorkflowOptions workflowOptions;
@@ -2179,7 +2183,7 @@ private ImmutableMap<String, Object> getEndpoints(Structure endpoints)
     // TODO(b/269526710): Enable more than one endpoint
     check(fields.size() == 1 && Iterables.getOnlyElement(fields).equals("destination"),
         "Temporarily core.action_migration only supports one endpoint called destination");
-    
+
     for (String fieldName : fields) {
       Object epProvider = endpoints.getValue(fieldName);
       check(epProvider instanceof EndpointProvider,

javatests/com/google/copybara/WorkflowTest.java

@@ -5377,4 +5377,38 @@ public void testInvalidMigrationName() {
             + ")\n",
         ".*Migration name 'foo[|] bad;name' doesn't conform to expected pattern.*");
   }
+
+  @Test
+  public void testCustomRevIdFormat_validUsingUnderscoreWithREV_ID() throws Exception {
+    origin.addSimpleChange(/*timestamp*/ 0);
+    extraWorkflowFields = ImmutableList.of("custom_rev_id = \"CUSTOM_REV_ID\"");
+    skylarkWorkflow("default", SQUASH).run(workdir, ImmutableList.of(HEAD));
+
+    ProcessedChange change = Iterables.getOnlyElement(destination.processed);
+    assertThat(change.getRevIdLabel()).isEqualTo("CUSTOM_REV_ID");
+  }
+
+  @Test(expected = ValidationException.class)
+  public void testCustomRevIdFormat_invalidUsingHyphenWithREV_ID() throws Exception {
+    origin.addSimpleChange(/*timestamp*/ 0);
+    extraWorkflowFields = ImmutableList.of("custom_rev_id = \"CUSTOM-REV_ID\"");
+    skylarkWorkflow("default", SQUASH).run(workdir, ImmutableList.of(HEAD));
+  }
+
+  @Test
+  public void testCustomRevIdFormat_validHyphenWithRevId() throws Exception {
+    origin.addSimpleChange(/*timestamp*/ 0);
+    extraWorkflowFields = ImmutableList.of("custom_rev_id = \"Custom-RevId\"");
+    skylarkWorkflow("default", SQUASH).run(workdir, ImmutableList.of(HEAD));
+
+    ProcessedChange change = Iterables.getOnlyElement(destination.processed);
+    assertThat(change.getRevIdLabel()).isEqualTo("Custom-RevId");
+  }
+
+  @Test(expected = ValidationException.class)
+  public void testCustomRevIdFormat_invalidUsingUnderscoreWithRevId() throws Exception {
+    origin.addSimpleChange(/*timestamp*/ 0);
+    extraWorkflowFields = ImmutableList.of("custom_rev_id = \"CUSTOM_RevId\"");
+    skylarkWorkflow("default", SQUASH).run(workdir, ImmutableList.of(HEAD));
+  }
 }