fix(codegen): variable allocation in StringStore (smithy-lang#1527)

Author: kuhe

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/util/StringStore.java

@@ -5,6 +5,7 @@
 
 package software.amazon.smithy.typescript.codegen.util;
 
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedList;
@@ -77,7 +78,9 @@ private String assignKey(String literal) {
      * Prefers the uppercase or word-starting letters.
      */
     private String allocateVariable(String literal) {
-        String[] sections = literal.split("[-_\\s]");
+        String[] sections = Arrays.stream(literal.split("[-_\\s]"))
+            .filter(s -> !s.isEmpty())
+            .toArray(String[]::new);
         StringBuilder v = new StringBuilder("_");
         Queue<Character> deconfliction = new LinkedList<>();
         if (sections.length > 1) {

smithy-typescript-codegen/src/test/java/software/amazon/smithy/typescript/codegen/util/StringStoreTest.java

@@ -0,0 +1,125 @@
+package software.amazon.smithy.typescript.codegen.util;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Objects;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class StringStoreTest {
+
+    @Test
+    void var() {
+        StringStore subject = new StringStore();
+        String sourceCode = """
+            const array = [
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s,
+                %s
+            ];
+            """.formatted(
+            subject.var("SomeObject"),
+            subject.var("some_object"),
+            subject.var("SomeObject"),
+            subject.var("some_object"),
+            subject.var("_"),
+            subject.var("__"),
+            subject.var("___"),
+            subject.var("_internal"),
+            subject.var("__internal"),
+            subject.var("___internal"),
+            subject.var("_internal_"),
+            subject.var("__internal__"),
+            subject.var("___internal__"),
+            subject.var("_two--words"),
+            subject.var("__twoWords__"),
+            subject.var("___TwoWords__"),
+            subject.var("$Symbol"),
+            subject.var("%Symbol"),
+            subject.var("   !)(@*#&$^%   "),
+            subject.var("   !)( @  )(@*#&$^* SmithyTypeScript# &)(@*#&$^  $^%   )(@*#&$^"),
+            subject.var("**Ack**Ack**"),
+            subject.var("Spaces Are Cool"),
+            subject.var("__why Would &&& YouName $something this...")
+        );
+
+        String[] expected = """
+            const _ = "_";
+            const _AA = "**Ack**Ack**";
+            const _S = "$Symbol";
+            const _SAC = "Spaces Are Cool";
+            const _SO = "SomeObject";
+            const _S_ = "   !)( @  )(@*#&$^* SmithyTypeScript# &)(@*#&$^  $^%   )(@*#&$^";
+            const _Sy = "%Symbol";
+            const _TW = "___TwoWords__";
+            const __ = "__";
+            const ___ = "___";
+            const ____ = "   !)(@*#&$^%   ";
+            const _i = "_internal";
+            const _in = "__internal";
+            const _int = "___internal";
+            const _inte = "_internal_";
+            const _inter = "__internal__";
+            const _intern = "___internal__";
+            const _so = "some_object";
+            const _tW = "__twoWords__";
+            const _tw = "_two--words";
+            const _wWYt = "__why Would &&& YouName $something this...";
+            
+            const array = [
+                _SO,
+                _so,
+                _SO,
+                _so,
+                _,
+                __,
+                ___,
+                _i,
+                _in,
+                _int,
+                _inte,
+                _inter,
+                _intern,
+                _tw,
+                _tW,
+                _TW,
+                _S,
+                _Sy,
+                ____,
+                _S_,
+                _AA,
+                _SAC,
+                _wWYt
+            ];
+            """.split("\n");
+        String[] actual = (subject.flushVariableDeclarationCode() + "\n"
+            + sourceCode).split("\n");
+
+        for (int i = 0; i < expected.length; ++i) {
+            assertEquals(
+                Objects.toString(i) + ": " + expected[i].trim(),
+                Objects.toString(i) + ": " + actual[i].trim()
+            );
+        }
+    }
+}