codeql/python/ql/test/TestUtilities/VerifyApiGraphs.qll

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/**
* A test query that verifies assertions about the API graph embedded in source-code comments.
*
* An assertion is a comment of the form `def=<path>` or `use=<path>`, and asserts that
* there is a def/use feature reachable from the root along the given path, and its
* associated data-flow node must start on the same line as the comment.
*
* We also support negative assertions of the form `MISSING: def <path>` or `MISSING: use <path>`, which assert
* that there _isn't_ a node with the given path on the same line.
*
* The query only produces output for failed assertions, meaning that it should have no output
* under normal circumstances.
*
* The syntax is made to look exactly like inline expectation tests, so that the tests
* can remain consistent with other Python tests.
*/
import python
import semmle.python.dataflow.new.DataFlow
import semmle.python.ApiGraphs
private DataFlow::Node getNode(API::Node nd, string kind) {
kind = "def" and
result = nd.getARhs()
or
kind = "use" and
result = nd.getAUse()
}
private string getLocStr(Location loc) {
exists(string filepath, int startline |
loc.hasLocationInfo(filepath, startline, _, _, _) and
result = filepath + ":" + startline
)
}
/**
* An assertion matching a data-flow node against an API-graph feature.
*/
class Assertion extends Comment {
string expectedKind;
string expectedLoc;
string path;
string polarity;
Assertion() {
exists(string txt, string rex |
txt = this.getText().trim() and
rex = "#\\$.*?((?:MISSING: )?)(def|use)=([\\w\\(\\)\"\\.]*).*"
|
polarity = txt.regexpCapture(rex, 1) and
expectedKind = txt.regexpCapture(rex, 2) and
path = txt.regexpCapture(rex, 3) and
expectedLoc = getLocStr(this.getLocation())
)
}
string getEdgeLabel(int i) {
// matches a single edge. E.g. `getParameter(1)` or `getMember("foo")`.
// The lookbehind/lookahead ensure that the boundary is correct, that is
// either the edge is next to a ".", or it's the end of the string.
result = path.regexpFind("(?<=\\.|^)([\\w\\(\\)\"]+)(?=\\.|$)", i, _).trim()
}
int getPathLength() { result = max(int i | exists(this.getEdgeLabel(i))) + 1 }
predicate isNegative() { polarity = "MISSING: " }
API::Node lookup(int i) {
i = 0 and
result = API::root()
or
result =
this.lookup(i - 1)
.getASuccessor(any(API::Label::ApiLabel label |
label.toString() = this.getEdgeLabel(i - 1)
))
}
API::Node lookup() { result = this.lookup(this.getPathLength()) }
predicate holds() { getLocStr(getNode(this.lookup(), expectedKind).getLocation()) = expectedLoc }
string tryExplainFailure() {
exists(int i, API::Node nd, string prefix, string suffix |
nd = this.lookup(i) and
i < getPathLength() and
not exists(this.lookup([i + 1 .. getPathLength()])) and
prefix = nd + " has no outgoing edge labelled " + this.getEdgeLabel(i) + ";" and
if exists(nd.getASuccessor())
then
suffix =
"it does have outgoing edges labelled " +
concat(string lbl |
exists(nd.getASuccessor(any(API::Label::ApiLabel label | label.toString() = lbl)))
|
lbl, ", "
) + "."
else suffix = "it has no outgoing edges at all."
|
result = prefix + " " + suffix
)
or
exists(API::Node nd, string kind | nd = this.lookup() |
exists(getNode(nd, kind)) and
not exists(getNode(nd, expectedKind)) and
result = "Expected " + expectedKind + " node, but found " + kind + " node."
)
or
exists(DataFlow::Node nd | nd = getNode(this.lookup(), expectedKind) |
not getLocStr(nd.getLocation()) = expectedLoc and
result =
"Node not found on this line (but there is one on line " + min(getLocStr(nd.getLocation())) +
")."
)
}
string explainFailure() {
if this.isNegative()
then (
this.holds() and
result = "Negative assertion failed."
) else (
not this.holds() and
(
result = this.tryExplainFailure()
or
not exists(this.tryExplainFailure()) and
result = "Positive assertion failed for unknown reasons."
)
)
}
}
query predicate failed(Assertion a, string explanation) { explanation = a.explainFailure() }