branch: elpa/buttercup
commit bb3fba35c38567e336243b8810d4baec6be44a38
Author: Ryan C. Thompson <r...@thompsonclan.org>
Commit: Ryan C. Thompson <r...@thompsonclan.org>
Properly handle return values and thrown signals in spies
Attempting to access the return valye of a spy context representing a
call that threw a signal now throws an error. Similarly, attempting to
access the thrown signal of a successful function call also throws an
error.
This is implemented by using two new structs derived from the
spy-context struct: one for successful calls and one for errors.
Ideally, we would use cl-defgeneric, but it is not available prior to
Emacs 25.1.
Tests are added for the new behavior, and several existing tests are
modified to accommodate it.
---
buttercup.el | 26 ++++++++++++++------------
docs/writing-tests.md | 35 +++++++++++++++++++++++++----------
tests/test-buttercup.el | 2 +-
3 files changed, 40 insertions(+), 23 deletions(-)
diff --git a/buttercup.el b/buttercup.el
index a360a4b..29d8a16 100644
--- a/buttercup.el
+++ b/buttercup.el
@@ -1023,10 +1023,14 @@ DESCRIPTION has the same meaning as in `xit'. FUNCTION
is ignored."
"A mapping of currently-defined spies to their contexts.")
(cl-defstruct spy-context
- args
- return-value
- thrown-signal
- current-buffer)
+ args current-buffer)
+;; The struct and slot names are kind of a cheat so that the accessor
+;; function names remain unchanged: `spy-context-return-value' and
+;; `spy-context-thrown-signal'.
+(cl-defstruct (spy-context-return (:include spy-context))
+ value)
+(cl-defstruct (spy-context-thrown (:include spy-context))
+ signal)
(defun spy-on (symbol &optional keyword arg)
"Create a spy (mock) for the function SYMBOL.
@@ -1118,10 +1122,9 @@ responsibility to ensure ARG is a command."
returned t)
(buttercup--spy-calls-add
this-spy-function
- (make-spy-context :args args
- :return-value return-value
- :thrown-signal nil
- :current-buffer (current-buffer)))
+ (make-spy-context-return :args args
+ :value return-value
+ :current-buffer (current-buffer)))
return-value)
(error
;; If returned is non-nil, then the error we caught
@@ -1129,10 +1132,9 @@ responsibility to ensure ARG is a command."
(unless returned
(buttercup--spy-calls-add
this-spy-function
- (make-spy-context :args args
- :return-value nil
- :thrown-signal err
- :current-buffer (current-buffer))))
+ (make-spy-context-thrown :args args
+ :signal err
+ :current-buffer (current-buffer))))
;; Regardless, we only caught this error in order to
;; record it, so we need to re-throw it.
(signal (car err) (cdr err)))))))
diff --git a/docs/writing-tests.md b/docs/writing-tests.md
index 643303c..9307f43 100644
--- a/docs/writing-tests.md
+++ b/docs/writing-tests.md
@@ -600,9 +600,9 @@ Finally, `spy-calls-reset` clears all tracking for a spy.
(expect (spy-calls-all 'set-foo)
:to-equal
- `(,(make-spy-context :current-buffer (current-buffer)
- :args '(123)
- :return-value nil))))
+ `(,(make-spy-context-return :current-buffer (current-buffer)
+ :args '(123)
+ :value nil))))
(it "has a shortcut to the most recent call"
(set-foo 123)
@@ -610,9 +610,9 @@ Finally, `spy-calls-reset` clears all tracking for a spy.
(expect (spy-calls-most-recent 'set-foo)
:to-equal
- (make-spy-context :current-buffer (current-buffer)
- :args '(456 "baz")
- :return-value nil)))
+ (make-spy-context-return :current-buffer (current-buffer)
+ :args '(456 "baz")
+ :value nil)))
(it "has a shortcut to the first call"
(set-foo 123)
@@ -620,9 +620,9 @@ Finally, `spy-calls-reset` clears all tracking for a spy.
(expect (spy-calls-first 'set-foo)
:to-equal
- (make-spy-context :current-buffer (current-buffer)
- :args '(123)
- :return-value nil)))
+ (make-spy-context-return :current-buffer (current-buffer)
+ :args '(123)
+ :value nil)))
(it "tracks the return values and error signals of each call"
;; Set up `set-foo' so that it can either return a value or throw
@@ -634,13 +634,28 @@ Finally, `spy-calls-reset` clears all tracking for a spy.
(error "Value must not be negative"))))
(expect (set-foo 1) :to-be 1)
(expect (set-foo -1) :to-throw 'error)
+ (expect (spy-context-return-p (spy-calls-first 'set-foo)))
(expect
(spy-context-return-value (spy-calls-first 'set-foo))
:to-be 1)
+ ;; Trying to get the thrown signal from a call that didn't throw a
+ ;; signal is an error
(expect
(spy-context-thrown-signal
+ (spy-calls-first 'set-foo))
+ :to-throw)
+
+ (expect (spy-context-thrown-p (spy-calls-most-recent 'set-foo)))
+ (expect
+ (spy-context-thrown-signal
+ (spy-calls-most-recent 'set-foo))
+ :to-equal '(error "Value must not be negative"))
+ ;; Trying to get the return value from a call that threw a signal
+ ;; raises an error
+ (expect
+ (spy-context-return-value
(spy-calls-most-recent 'set-foo))
- :to-equal (list 'error "Value must not be negative")))
+ :to-throw))
(it "can be reset"
(set-foo 123)
diff --git a/tests/test-buttercup.el b/tests/test-buttercup.el
index c2e8317..6368202 100644
--- a/tests/test-buttercup.el
+++ b/tests/test-buttercup.el
@@ -933,7 +933,7 @@
(expect (test-function-throws-on-negative -5) :to-throw 'error)
(expect (spy-context-thrown-signal
(spy-calls-first 'test-function-throws-on-negative))
- :to-be nil)
+ :to-throw)
(expect (spy-context-thrown-signal
(spy-calls-most-recent 'test-function-throws-on-negative))
:to-equal '(error "x is less than zero"))))))
