Add more tests for constants in tree-sitter grammar (#247)

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* All new code requires tests to ensure against regressions

### Description of the Change

The PR adds more tests for various types of constants in situations when they are used as class fields, method names, field names, and in switch statements.

### Alternate Designs

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### Benefits

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### Possible Drawbacks

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### Applicable Issues

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Author: sadikovi

spec/tree-sitter-java-spec.coffee

@@ -242,7 +242,11 @@ describe 'Tree-sitter based Java grammar', ->
 
   it 'tokenizes constants', ->
     tokens = tokenizeLines '''
-      String CONSTANT_STR = "abc";
+      String CONSTANT_STR = "value";
+      int CONST0 = 0;
+      int CONST_1 = 1;
+      String A1_B2_C3 = "abc";
+      String A$_B$_C$ = "abc";
       a = CONSTANT + obj.func();
       b = conf.get(CONSTANT_ANOTHER);
       c = Integer.MAX_VALUE;
@@ -252,12 +256,36 @@ describe 'Tree-sitter based Java grammar', ->
     '''
 
     expect(tokens[0][2]).toEqual value: 'CONSTANT_STR', scopes: ['source.java', 'constant.other']
-    expect(tokens[1][3]).toEqual value: 'CONSTANT', scopes: ['source.java', 'constant.other']
-    expect(tokens[2][6]).toEqual value: 'CONSTANT_ANOTHER', scopes: ['source.java', 'constant.other']
-    expect(tokens[3][5]).toEqual value: 'MAX_VALUE', scopes: ['source.java', 'constant.other']
-    expect(tokens[4][3]).toEqual value: 'A1_B2_C3', scopes: ['source.java', 'constant.other']
-    expect(tokens[5][3]).toEqual value: 'A1_B2_C$', scopes: ['source.java', 'constant.other']
-    expect(tokens[6][5]).toEqual value: 'A1_B2_C3', scopes: ['source.java', 'constant.other']
+    expect(tokens[1][2]).toEqual value: 'CONST0', scopes: ['source.java', 'constant.other']
+    expect(tokens[2][2]).toEqual value: 'CONST_1', scopes: ['source.java', 'constant.other']
+    expect(tokens[3][2]).toEqual value: 'A1_B2_C3', scopes: ['source.java', 'constant.other']
+    expect(tokens[4][2]).toEqual value: 'A$_B$_C$', scopes: ['source.java', 'constant.other']
+    expect(tokens[5][3]).toEqual value: 'CONSTANT', scopes: ['source.java', 'constant.other']
+    expect(tokens[6][6]).toEqual value: 'CONSTANT_ANOTHER', scopes: ['source.java', 'constant.other']
+    expect(tokens[7][5]).toEqual value: 'MAX_VALUE', scopes: ['source.java', 'constant.other']
+    expect(tokens[8][3]).toEqual value: 'A1_B2_C3', scopes: ['source.java', 'constant.other']
+    expect(tokens[9][3]).toEqual value: 'A1_B2_C$', scopes: ['source.java', 'constant.other']
+    expect(tokens[10][5]).toEqual value: 'A1_B2_C3', scopes: ['source.java', 'constant.other']
+
+  it 'tokenizes constants in switch statement', ->
+    tokens = tokenizeLines '''
+      switch (value) {
+        case CONST: break;
+        case CONST_STR: break;
+        case CONST0: break;
+        case CONST_1: break;
+        case C0_STR1_DEF2: break;
+        case C$_STR$_DEF$: break;
+        default: break;
+      }
+    '''
+
+    expect(tokens[1][3]).toEqual value: 'CONST', scopes: ['source.java', 'constant.other']
+    expect(tokens[2][3]).toEqual value: 'CONST_STR', scopes: ['source.java', 'constant.other']
+    expect(tokens[3][3]).toEqual value: 'CONST0', scopes: ['source.java', 'constant.other']
+    expect(tokens[4][3]).toEqual value: 'CONST_1', scopes: ['source.java', 'constant.other']
+    expect(tokens[5][3]).toEqual value: 'C0_STR1_DEF2', scopes: ['source.java', 'constant.other']
+    expect(tokens[6][3]).toEqual value: 'C$_STR$_DEF$', scopes: ['source.java', 'constant.other']
 
   it 'tokenizes reserved keywords', ->
     tokens = tokenizeLine 'const value;'