Senior Symposium Friday, April 16 12:30 PM 12:45 PM 2 Tuesday, - PowerPoint PPT Presentation

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public DnaStrand cutAndSplice(String enzyme, String splicee) { � int enzymeStart = dnaSequence.indexOf(enzyme); � � StringDNA � if (enzymeStart == -1) { � � return new StringDNAStrand(); � � } Strand � � � StringBuilder recombStrand = new StringBuilder(); � � � int enzymeEnd = 0; � while (enzymeStart != -1) { � � numBreaks++; � � � � � recombStrand.append(dnaSequence.substring(enzymeEnd, enzymeStart)); � � recombStrand.append(splicee); � � � � � enzymeEnd = enzymeStart + enzyme.length(); � � enzymeStart = dnaSequence.indexOf(enzyme, enzymeEnd); � � } � � � recombStrand.append(dnaSequence.substring(enzymeEnd)); � return new StringDNAStrand (recombStrand.toString()); � } 3 Building the String dna “ACGTGAGTGG” enzyme “GTG” splicee “AAAA ” “ACAAAA ” recombStrand.append(dna.substring(enzymeEnd, enzymeStart)); recombStrand.append(splicee); 4 Tuesday, April 13, 2010

Building the String dna “ACGTGAGTGG” enzyme “GTG” splicee “AAAA ” “ACAAAAAAAAA ” recombStrand.append(dna.substring(enzymeEnd, enzymeStart)); recombStrand.append(splicee); 5 Building the String dna “ACGTGAGTGG” enzyme “GTG” splicee “AAAA ” On each append call, “ACAAAAAAAAAG” we copy the splicee into the StringBuilder. recombStrand.append(dna.substring(enzymeEnd, enzymeStart)); recombStrand.append(splicee); 6 Tuesday, April 13, 2010

public DnaStrand cutAndSplice(String enzyme, String splicee) { � if (head.getNext() != null) { � � throw new IllegalStateException ("Cannot cut and splice a link strand containing more than one node."); � � } � � � LinkedListDNAStrand recombStrand = new LinkedListDNAStrand(); � int enzymeStart = head.value.indexOf(enzyme); � if (enzymeStart == -1) { LinkedList � � return recombStrand; � � } � int enzymeEnd = 0; DNAStrand � while (enzymeStart != -1) { � � numBreaks++; � � recombStrand.append(head.value.substring(enzymeEnd, enzymeStart)); � � recombStrand.append(splicee); � � enzymeEnd = enzymeStart + enzyme.length(); � � enzymeStart = head.value.indexOf(enzyme, enzymeEnd); � � } � recombStrand.append(head.value.substring(enzymeEnd)); � return recombStrand; � } 7 recombStrand.append(splicee); LinkedList private LinkedListDNAStrand append(String dna) { DNAStrand � Node newNode = new Node(dna); � if (head == null) { � � head = newNode; � } splicee, dna, value all � � else { refer to the same � � tail.setNext(newNode); String object � } � tail = newNode; � � length = length + dna.length(); � We construct the linked � return this; } list without ever copying the splicee! � � public Node (String value) { � � � this.value = value; � � } 8 Tuesday, April 13, 2010

Building the Linked List Making the splicee dna “ACGTGAGTGG” longer does not enzyme “GTG” increase the cost splicee “AAAA ” of building the linked list! “G” “AC” “A ” recombStrand.append(dna.substring(enzymeEnd, enzymeStart)); recombStrand.append(splicee); 9 Goal of Testing Demonstrate that the program is correct What does “correct” mean? It meets its specification Specification: English description of what the program should do. What if the specification is wrong?!? NOT a proof that the program is correct! 10 Tuesday, April 13, 2010

General Testing Strategy Want to generalize from the test input to make claims about all input Divide input into a set of equivalence classes Choose 1 (or a small number) of test input from each equivalence class Assume that if the program works on the test input, it will work on all input. KEY: Pick your equivalence classes well! 11 Finding Equivalence Classes Black-box testing Examine the specification White-box testing Examine the code 12 Tuesday, April 13, 2010

White Box Testing Execute every statement Execute every true & false branch Loops: 0 iterations 1 iteration many iterations Boundary conditions: minimal values maximal values 13 White Box Testing Example / / Return the index where the value is in a. Return -1 / / if the value is not in the array. / / Precondition: a must be sorted. int search (int[] a, int value) { for (int i = 0; i < a.length; i++) { if (a[i] == value) { return i; } } � return -1; } 14 Tuesday, April 13, 2010

White Box Testing Example 2 / / Return the index where the value is in a. Return -1 / / if the value is not in the array. / / Precondition: a must be sorted. int search (int[] a, int value) { int low = 0; int high = a.length - 1; int middle; while( low < high ) � { � � middle = ( low + high ) / 2; � � � � if( value == a[middle] ) � � � return middle; � � else if( value < a[middle] ) � � � high = middle - 1; � � � else � � � low = middle + 1; � � } � � return -1; } 15 Testing Phases Our emphasis Unit testing - test individual class Integration testing - test groups of interacting classes System testing - test entire system integrated with real hardware, databases, etc. Acceptance testing - testing done by customer to decide if software does what they want 16 Tuesday, April 13, 2010

“code-a-little, test-a-little” Allows us to find errors early Leaves less question about where the error is. It’ s probably in the code we just wrote. Test-driven development - develop test program BEFORE the code to be tested! 17 Structured Walkthroughs Carefully trace your code to be sure it does what you intend. Don’ t take shortcuts. Best to do with another person. Explain the code. Let the other person critique. 18 Tuesday, April 13, 2010

Structured Walkthrough Example / / Return the index where the value is in a. Return -1 / / if the value is not in the array. / / Precondition: a must be sorted. int search (int[] a, int value) { int low = 0; int high = a.length - 1; int middle; while( low < high ) � { � � middle = ( low + high ) / 2; � � � � if( value == a[middle] ) � � � return middle; � � else if( value < a[middle] ) � � � high = middle - 1; � � � else � � � low = middle + 1; � � } � � return -1; } 19 Tuesday, April 13, 2010