Fix expansion option output formatting in html output

Like the terminal output, there was some discrepancy between the expansion function and static expansion behavior. Also adds html usage output tests.

PiperOrigin-RevId: 165584454

1 files changed, 19 insertions, 12 deletions

diff --git a/src/main/java/com/google/devtools/common/options/OptionsUsage.java b/src/main/java/com/google/devtools/common/options/OptionsUsage.java
index 61829e2d99..8e36c4a84d 100644
--- a/src/main/java/com/google/devtools/common/options/OptionsUsage.java
+++ b/src/main/java/com/google/devtools/common/options/OptionsUsage.java
@@ -201,22 +201,29 @@ class OptionsUsage {
       usage.append(paragraphFill(escaper.escape(annotation.help()), /*indent=*/ 0, /*width=*/ 80));
       usage.append('\n');
     }
-    ImmutableList<String> expansion = getExpansionIfKnown(optionField, optionsData);
-    if (expansion == null) {
-      usage.append("    Expands to unknown options.<br>\n");
-    } else if (!expansion.isEmpty()) {
+
+    if (!optionsData.getExpansionDataForField(optionField).isEmpty()) {
+      // If this is an expansion option, list the expansion if known, or at least specify that we
+      // don't know.
       usage.append("<br/>\n");
-      StringBuilder expandsMsg = new StringBuilder("Expands to:<br/>\n");
-      for (String exp : expansion) {
-        // TODO(ulfjack): Can we link to the expanded flags here?
-        expandsMsg
-            .append("&nbsp;&nbsp;<code>")
-            .append(escaper.escape(exp))
-            .append("</code><br/>\n");
+      ImmutableList<String> expansion = getExpansionIfKnown(optionField, optionsData);
+      StringBuilder expandsMsg;
+      if (expansion == null) {
+        expandsMsg = new StringBuilder("Expands to unknown options.<br/>\n");
+      } else {
+        Preconditions.checkArgument(!expansion.isEmpty());
+        expandsMsg = new StringBuilder("Expands to:<br/>\n");
+        for (String exp : expansion) {
+          // TODO(ulfjack): Can we link to the expanded flags here?
+          expandsMsg
+              .append("&nbsp;&nbsp;<code>")
+              .append(escaper.escape(exp))
+              .append("</code><br/>\n");
+        }
       }
       usage.append(expandsMsg.toString());
-      usage.append('\n');
     }
+
     usage.append("</dd>\n");
   }