In that case, though I'm certain the masking method others have posted is the best solution, here's a recursive/substr method, just for fun:

#!/usr/bin/env perl
use Modern::Perl;

sub findstr {
    if( @_ == 1 ){
        return shift;
    }
    my $x = shift;
    my $y = shift;
    my $l = length $x > length $y ? length $y : length $x;
    for( my $i=$l; $i>0; $i--){
        if( substr($x, 0, $i) eq substr($y, 0, $i)){
            return findstr(substr($x,0,$i), @_);
        }
    }
}

my @array_of_test_names = (
    'History - Family History - Suite with Patient - Clinic - Select R
+emove(-) Icon of Relative. - Clinic',
    'History - Family History - Suite with Patient - Clinic - Save aft
+er Entering values in all fields - Clinic',
    'History - Family History - Suite with Patient - Clinic - Select A
+dd(+) Icon of Relative. - Clinic',
    'History - Family History - Suite with Patient - Clinic - Multiple
+ selection of relatives - Clinic',
    'History - Family History - Suite with Patient - Clinic - Interact
+ion Checking message not provided if procedure code is selected - Cli
+nic',
    'History - Family History - Suite with Patient - Clinic - Interact
+ion Checking message provided if no procedure code is selected - Clin
+ic',
);

my $match = findstr(@array_of_test_names);
say $match;
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