Make it possible to ignore comment lines when comparing schemas (#2690)

We now pin to postgreSQL v17 when running tests, which means that minor
version might increase without our intervention. This causes (at least)
the comment in the golden schema to change, and failing the test as a
result.

This PR adds the ability to strip lines that we deem as comment from the
comparison, so we don't have to do trivial upgrades to the gold schema
whenever there's minor version upgrade.

common/src/testing/java/google/registry/testing/truth/TextDiffSubject.java

@@ -35,6 +35,7 @@ import com.google.common.truth.SimpleSubjectBuilder;
 import com.google.common.truth.Subject;
 import java.io.IOException;
 import java.net.URL;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Comparator;
 import java.util.List;
@@ -63,6 +64,7 @@ public class TextDiffSubject extends Subject {
 
   private final ImmutableList<String> actual;
   private DiffFormat diffFormat = DiffFormat.SIDE_BY_SIDE_MARKDOWN;
+  private List<String> comments = new ArrayList<>();
 
   protected TextDiffSubject(FailureMetadata metadata, List<String> actual) {
     super(metadata, actual);
@@ -83,10 +85,22 @@ public class TextDiffSubject extends Subject {
     return this;
   }
 
+  /** If set, ignore lines that start with the given string. */
+  public TextDiffSubject ignoringLinesThatStartWith(String comment) {
+    comments.add(comment);
+    return this;
+  }
+
+  private ImmutableList<String> filterComments(List<String> lines) {
+    return lines.stream()
+        .filter(line -> comments.stream().noneMatch(line::startsWith))
+        .collect(ImmutableList.toImmutableList());
+  }
+
   public void hasSameContentAs(List<String> expectedContent) {
     checkNotNull(expectedContent, "expectedContent");
-    ImmutableList<String> expected = ImmutableList.copyOf(expectedContent);
-    if (expected.equals(actual)) {
+    ImmutableList<String> expected = filterComments(expectedContent);
+    if (filterComments(expected).equals(filterComments(actual))) {
       return;
     }
     String diffString = diffFormat.generateDiff(expected, actual);

db/src/test/java/google/registry/sql/flyway/SchemaTest.java

@@ -115,6 +115,7 @@ class SchemaTest {
             Joiner.on(File.separatorChar).join(MOUNTED_RESOURCE_PATH, DUMP_OUTPUT_FILE));
 
     assertThat(dumpedSchema)
+        .ignoringLinesThatStartWith("--")
         .hasSameContentAs(Resources.getResource("sql/schema/nomulus.golden.sql"));
   }