Disallow line appearing more than once

I'm not an expert on Cobertura, but it seems confusing to have stuff
like:

```
<line number="5" hits="1"></line>
<line number="5" hits="0"></line>
```

I decided to treat this situation in a pessimistic way - i.e.: if the
second entry for a line number is lower than the previous one, then we
update the hit count down; but we never update it up. In other words, if
we ever see a 0 for a line, we mark the line uncovered, even if we
previously saw a 1.

cobertura.go

@@ -79,6 +79,22 @@ func (lines Lines) NumLinesWithHits() (numLinesWithHits int64) {
 	return numLinesWithHits
 }
 
+// AddOrUpdateLine adds a line if it is a different line than the last line recorded.
+// If it's the same line as the last line recorded then we update the hits down
+// if the new hits is less; otherwise just leave it as-is
+func (lines *Lines) AddOrUpdateLine(lineNumber int, hits int64) {
+	if len(*lines) > 0 {
+		lastLine := (*lines)[len(*lines)-1]
+		if lineNumber == lastLine.Number {
+			if hits < lastLine.Hits {
+				lastLine.Hits = hits
+			}
+			return
+		}
+	}
+	*lines = append(*lines, &Line{Number: lineNumber, Hits: hits})
+}
+
 // HitRate returns a float32 from 0.0 to 1.0 representing what fraction of lines
 // have hits
 func (method Method) HitRate() float32 {

gocover-cobertura.go

@@ -147,7 +147,7 @@ func (v *fileVisitor) method(n *ast.FuncDecl) *Method {
 			continue
 		}
 		for i := b.StartLine; i <= b.EndLine; i++ {
-			method.Lines = append(method.Lines, &Line{Number: i, Hits: int64(b.Count)})
+			method.Lines.AddOrUpdateLine(i, int64(b.Count))
 		}
 	}
 	return method

gocover-cobertura_test.go

@@ -180,45 +180,42 @@ func TestConvertSetMode(t *testing.T) {
 	if c.Methods == nil || len(c.Methods) != 1 {
 		t.Fatal()
 	}
-	if c.Lines == nil || len(c.Lines) != 5 { // Why 5 lines? hmm...
-		t.Fatal()
+	if c.Lines == nil || len(c.Lines) != 4 {
+		t.Errorf("Expected 4 lines but got %d", len(c.Lines))
 	}
 
 	m := c.Methods[0]
 	if m.Name != "Func1" {
 		t.Error()
 	}
-	if m.Lines == nil || len(m.Lines) != 5 {
-		t.Fatal()
+	if c.Lines == nil || len(c.Lines) != 4 {
+		t.Errorf("Expected 4 lines but got %d", len(c.Lines))
 	}
 
 	var l *Line
 	if l = m.Lines[0]; l.Number != 4 || l.Hits != 1 {
 		t.Errorf("unmatched line: Number:%d, Hits:%d", l.Number, l.Hits)
 	}
-	if l = m.Lines[1]; l.Number != 5 || l.Hits != 1 {
-		t.Errorf("unmatched line: Number:%d, Hits:%d", l.Number, l.Hits)
-	}
-	if l = m.Lines[2]; l.Number != 5 || l.Hits != 0 {
+	if l = m.Lines[1]; l.Number != 5 || l.Hits != 0 {
 		t.Errorf("unmatched line: Number:%d, Hits:%d", l.Number, l.Hits)
 	}
-	if l = m.Lines[3]; l.Number != 6 || l.Hits != 0 {
+	if l = m.Lines[2]; l.Number != 6 || l.Hits != 0 {
 		t.Errorf("unmatched line: Number:%d, Hits:%d", l.Number, l.Hits)
 	}
-	if l = m.Lines[4]; l.Number != 7 || l.Hits != 0 {
+	if l = m.Lines[3]; l.Number != 7 || l.Hits != 0 {
 		t.Errorf("unmatched line: Number:%d, Hits:%d", l.Number, l.Hits)
 	}
 
 	if l = c.Lines[0]; l.Number != 4 || l.Hits != 1 {
 		t.Errorf("unmatched line: Number:%d, Hits:%d", l.Number, l.Hits)
 	}
-	if l = c.Lines[1]; l.Number != 5 || l.Hits != 1 {
+	if l = c.Lines[1]; l.Number != 5 || l.Hits != 0 {
 		t.Errorf("unmatched line: Number:%d, Hits:%d", l.Number, l.Hits)
 	}
-	if l = c.Lines[2]; l.Number != 5 || l.Hits != 0 {
+	if l = c.Lines[2]; l.Number != 6 || l.Hits != 0 {
 		t.Errorf("unmatched line: Number:%d, Hits:%d", l.Number, l.Hits)
 	}
-	if l = c.Lines[3]; l.Number != 6 || l.Hits != 0 {
+	if l = c.Lines[3]; l.Number != 7 || l.Hits != 0 {
 		t.Errorf("unmatched line: Number:%d, Hits:%d", l.Number, l.Hits)
 	}