clitest: Sanitize diff output some more

tests/cli-test-xml/compare/virt-xml-edit-clear-clock.xml

@@ -9,7 +9,7 @@
    <on_poweroff>destroy</on_poweroff>
    <on_reboot>restart</on_reboot>
    <on_crash>restart</on_crash>
-@@ -369,4 +364,5 @@
+@@
        <address type="isa" iobase="0x505"/>
      </panic>
    </devices>

tests/cli-test-xml/compare/virt-xml-edit-clear-cpu.xml

@@ -21,7 +21,7 @@
    <clock offset="utc">
      <timer name="rtc" tickpolicy="catchup"/>
      <timer name="pit" tickpolicy="delay"/>
-@@ -369,4 +352,5 @@
+@@
        <address type="isa" iobase="0x505"/>
      </panic>
    </devices>

tests/cli-test-xml/compare/virt-xml-edit-simple-cpu.xml

@@ -9,7 +9,7 @@
      <feature policy="require" name="tm2"/>
      <feature policy="require" name="est"/>
      <feature policy="require" name="ss"/>
-@@ -53,6 +53,7 @@
+@@
      <feature policy="require" name="ds_cpl"/>
      <feature policy="require" name="xtpr"/>
      <feature policy="require" name="acpi"/>

tests/cli-test-xml/compare/virt-xml-edit-simple-memory.xml

@@ -8,7 +8,7 @@
    <blkiotune>
      <weight>100</weight>
      <device>
-@@ -14,7 +14,6 @@
+@@
      </device>
    </blkiotune>
    <memoryBacking>

tests/cli-test-xml/compare/virt-xml-edit-simple-metadata.xml

@@ -12,7 +12,7 @@
    <memory unit="KiB">409600</memory>
    <currentMemory unit="KiB">204800</currentMemory>
    <blkiotune>
-@@ -369,4 +369,5 @@
+@@
        <address type="isa" iobase="0x505"/>
      </panic>
    </devices>

tests/cli-test-xml/compare/virt-xml-edit-simple-vcpus.xml

@@ -6,7 +6,7 @@
    <numatune>
      <memory mode="interleave" placement="auto"/>
    </numatune>
-@@ -53,6 +53,7 @@
+@@
      <feature policy="require" name="ds_cpl"/>
      <feature policy="require" name="xtpr"/>
      <feature policy="require" name="acpi"/>

tests/cli-test-xml/compare/virt-xml-remove-disk-path.xml

@@ -10,7 +10,7 @@
      <disk type="dir" device="floppy">
        <source dir="/tmp"/>
        <target dev="fdb" bus="fdc"/>
-@@ -92,12 +86,6 @@
+@@
        <target dev="hdb" bus="ide"/>
        <readonly/>
        <address type="drive" controller="0" bus="0" target="0" unit="1"/>

tests/clitest.py

@@ -248,7 +248,15 @@ class Command(object):
                     file(filename, "w").write(output)
 
                 if "--print-diff" in self.argv and output.count("\n") > 3:
-                    output = "\n".join(output.splitlines()[3:])
+                    # 1) Strip header
+                    # 2) Simplify context lines to reduce churn when
+                    #    libvirt or testdriver changes
+                    newlines = []
+                    for line in output.splitlines()[3:]:
+                        if line.startswith("@@"):
+                            line = "@@"
+                        newlines.append(line)
+                    output = "\n".join(newlines)
 
                 utils.diff_compare(output, filename)