Propagate source locations in expect macro #175
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zainab-ali
commented
Jul 11, 2025
| @@ -30,7 +30,7 @@ object TracingTests extends SimpleIOSuite { | |||
| val locations = e.head.locations.toList | |||
| val paths = locations.map(_.fileRelativePath).map(standardise) | |||
| forEach(paths)(p => expect(p == thisFile)) && | |||
| expect(locations.map(_.line).distinct.size == 4) | |||
| expect(locations.map(_.line).distinct.size == 3) | |||
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This behaviour has changed.
Previously, the locations would be:
val result = isOdd(2) // Line 24
.traced(here) // Line 25
.traced(here) // Line 26
...
def isOdd(i: Int)(implicit loc: SourceLocation): Expectations =
expect(i % 2 == 1).traced(loc) // Line 39, since `expect` would capture it's own location
With this changeset, expect doesn't capture its location, and uses the source location passed to isOdd instead. This means we no longer get line 39 as part of the trace.
This aligns the behaviour to other expectations. We could replace expect(1 % 2 == 1) with expect.eql(1 % 2, 1) and the trace would still have three locations.
zainab-ali
commented
Jul 11, 2025
| @@ -181,7 +181,7 @@ object DogFoodTests extends IOSuite { | |||
| | of | |||
| | multiline | |||
| | (failure) | |||
| | assertion failed (modules/framework-cats/shared/src/test/scala/Meta.scala:34) | |||
| | assertion failed (src/main/DogFoodTests.scala:5) | |||
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These tests now display the implicit source location defined in the test suite object.
Baccata
approved these changes
Jul 14, 2025
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All weaver expectations have an implicit
SourceLocationparameter. Developers can use this to customize the location displayed in failure messages. For example:The
expectmacros don't do this. Instead, they synthezise the source location to be that of the macro call site.This PR modifies the macros to support an implicit location.
Compatibility
This change is binary compatible since it only alters macro signatures. It's source compatible, in the sense that all existing calls to expect should still compile.