diff --git a/MathPadTests/MPExpressionTests.m b/MathPadTests/MPExpressionTests.m
index c5d5baf..35458e0 100644
--- a/MathPadTests/MPExpressionTests.m
+++ b/MathPadTests/MPExpressionTests.m
@@ -18,19 +18,32 @@
 @implementation MPExpressionTests
 
 - (void)testInitialization {
-    MPExpression *emptyExpression = [[MPExpression alloc] init];
-    MPExpression *stringExpression = [[MPExpression alloc] initWithString:@"1234+5678"];
-    MPExpression *functionExpression = [[MPExpression alloc] initWithFunction:[[MPFunction alloc] init]];
-    MPExpression *complexExpression = [[MPExpression alloc] initWithSymbols:@[@"1234", [[MPFunction alloc] init], @"17", [[MPFunction alloc] init]]];
+    // Test empty expression
+    MPExpression *testExpression = [[MPExpression alloc] init];
+    XCTAssertEqual([testExpression numberOfSymbols], 0);
+
+    // Test expression with string
+    testExpression = [[MPExpression alloc] initWithString:@"1234+5678"];
+    XCTAssertEqual([testExpression numberOfSymbols], 1);
+    XCTAssertEqualObjects([testExpression symbolAtIndex:0], @"1234+5678");
     
-    XCTAssertEqual([emptyExpression numberOfSymbols], 0);
-    XCTAssertEqual([stringExpression numberOfSymbols], 1);
-    XCTAssertEqual([functionExpression numberOfSymbols], 1);
-    XCTAssertEqual([complexExpression numberOfSymbols], 4);
+    // Test expression with function
+    testExpression = [[MPExpression alloc] initWithFunction:[[MPFunction alloc] init]];
+    XCTAssertEqual([testExpression numberOfSymbols], 1);
+    XCTAssertEqualObjects([testExpression symbolAtIndex:0], [[MPFunction alloc] init]);
     
-    XCTAssertEqualObjects([stringExpression symbolAtIndex:0], @"1234+5678");
-    XCTAssertEqualObjects([functionExpression symbolAtIndex:0], [[MPFunction alloc] init]);
-    XCTAssertEqualObjects([complexExpression symbolAtIndex:2], @"17");
+    testExpression = [[MPExpression alloc] initWithSymbols:@[@"1234", [[MPFunction alloc] init], @"17", [[MPFunction alloc] init]]];
+    XCTAssertEqual([testExpression numberOfSymbols], 4);
+    XCTAssertEqualObjects([testExpression symbolAtIndex:2], @"17");
+    
+    // Test expression with subsequent strings
+    testExpression = [[MPExpression alloc] initWithSymbols:@[@"1234", @"5678"]];
+    XCTAssertEqual([testExpression numberOfSymbols], 1);
+    XCTAssertEqualObjects([testExpression symbolAtIndex:0], @"12345678");
+    
+    // Test expression with only empty string
+    testExpression = [[MPExpression alloc] initWithString:@""];
+    XCTAssertEqual([testExpression numberOfSymbols], 0);
 }
 
 - (void)testSubexpressions {
diff --git a/MathPadTests/MPMutableExpressionTests.m b/MathPadTests/MPMutableExpressionTests.m
index 7a5cda9..6bed1da 100644
--- a/MathPadTests/MPMutableExpressionTests.m
+++ b/MathPadTests/MPMutableExpressionTests.m
@@ -27,11 +27,13 @@
     XCTAssertEqual([testExpression numberOfSymbols], 3);
     // 12678 [] 90
     
-    [testExpression insertFunction:[[MPFunction alloc] init] atIndex:2];
+    [testExpression insertFunction:[[MPFunction alloc] init]
+                           atIndex:2];
     XCTAssertEqual([testExpression numberOfSymbols], 5);
     // 12 [] 678 [] 90
     
-    [testExpression replaceSymbolsInRange:NSMakeRange(2, 5) withSymbols:@[[[MPFunction alloc] init]]];
+    [testExpression replaceSymbolsInRange:NSMakeRange(2, 5)
+                              withSymbols:@[[[MPFunction alloc] init]]];
     XCTAssertEqual([testExpression numberOfSymbols], 3);
     // 12 [] 90