src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/protocol/parser/tokenizer/TokenClassifier.java

@@ -48,7 +48,7 @@ public class TokenClassifier {
     }
 
     private static void validateSeparator(List<RawToken> rawTokens, int index) {
-        boolean missingKey = index == 0 || rawTokens.get(index - 1).type() != RawTokenType.WORD;
+        boolean missingKey = index <= 1 || rawTokens.get(index - 1).type() != RawTokenType.WORD;
 
         boolean missingValue =
                 index + 1 >= rawTokens.size()

src/test/java/ch/unibas/dmi/dbis/cs108/casono/server/network/protocol/parser/tokenizer/TokenClassifierTest.java

@@ -63,6 +63,15 @@ public class TokenClassifierTest {
         assertEquals("Expected VALUE after '='", ex.getMessage());
     }
 
+    @Test
+    void testMissingKeyBeforeSeparatorThrows() {
+        List<RawToken> raw = Tokenizer.tokenize("CMD =VALUE");
+
+        TokenizerException ex =
+                assertThrows(TokenizerException.class, () -> TokenClassifier.classify(raw));
+        assertEquals("Expected KEY before '='", ex.getMessage());
+    }
+
     @Test
     void testNextWordIsKeyThrows() {
         List<RawToken> raw = Tokenizer.tokenize("CMD KEY1=KEY2=42");