add fail-fast guard for Kotlin inline function mocking (#1030) #1421
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…into fix/1030-inline-function-error # Conflicts: # modules/mockk/src/jvmTest/kotlin/io/mockk/it/InlineMemberFunctionFailFastTest.kt
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Thanks for looking into this! |
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| val kotlinFunction = this.kotlinFunction | ||
| if (kotlinFunction != null && kotlinFunction.isInline) return true | ||
| } catch (_: Throwable) { |
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Why are you catching Throwable here? Can't we be more specific and catch just the Exception types that we expect to be thrown?
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Thanks for the catch! 👍
I agree that catching Throwable is too broad here. I’ll narrow it down to the concrete cases we actually expect when accessing kotlinFunction (e.g., KotlinReflectionInternalError and UnsupportedOperationException).
In those cases, I’ll fall back to the @kotlin.internal.InlineOnly annotation check.
I’ll push an update shortly!
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| private fun inlineHint(): String = |
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Why don't we inline (pun intended :P ) this instead of having it in a separate method, if it's used only once?
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Yeah, fair point. 😄
I only pulled inlineHint() out so it’d be easier to tweak or remove later, but since it’s only used once, I’m fine with just inlining it.
I’ll make that change and push an update soon.
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| @Test | ||
| fun stubOfInlineFunctionViaReflectionThrowsFailFastError() { |
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📋 Review Summary
This PR does a great job of improving the error messages when trying to mock Kotlin inline functions. The changes are clear and the new tests provide good coverage. I've added a couple of minor suggestions to improve code style and reduce duplication.
🔍 General Feedback
- The new error messages are much more descriptive and will be very helpful for users.
- The addition of tests for the new behavior is excellent.
- The approach to detect inline functions seems robust.
Fixes #1030 : "Throwing a descriptive error upon encountering inline function"
Kotlin
inlinefunctions are inlined at the call site, meaning their actual method calls disappear at runtime.As a result, proxy-based mocking is fundamentally impossible.
Previously, attempts to mock inline functions would fail with vague messages like:
"Failed matching mocking signature..."or"Missing mocked calls...", making it difficult to debug.This change classifies such failures into two clear categories and provides more actionable feedback: