As others have commented here, you have a deceptively tricky bit of work here to parse out this data because of the commas both inside and outside the quotes. If you have control over the format of testhash.txt you should consider changing that. An easy-to-parse format would be to separate key-value sets each on their own line. Thus:

     key1,value1
     key2,value2
     key3,value3
     key4,value4
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On the other hand if you need to use the file as it is, and if you know it will always have exactly four key-value pairs in the format you have given, this code will allow you to parse it into a hash.

open HANDLE, 'testhash.txt' or die "Can't open: $!";
my $data = <HANDLE>;
close HANDLE;
chomp $data;
my %hash = $data =~ /'([^,]+),([^']+)',
                     '([^,]+),([^']+)',
                     '([^,]+),([^']+)',
                     '([^,]+),([^']+)'/x;

# demo use of the hash to access results
foreach my $key (keys %hash) {
   print "$key $hash{$key}\n";
}
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It ain't elegant or flexible, but it will satisfy your immediate need. If there are going to be spaces after the commas or other interesting things, that can be dealt with in this approach. But at a certain point, you would need to consider a more robust approach (i.e. a CSV module from CPAN). Which would be a bit of overkill just to grab four key-value pairs.