࿨ా୎ਓʢ!U@XBEBʣ αόϯφศΓ ࣗಈςετʹؔ͢Δ࿈ࡌͰಘΒΕͨ஌ݟͷ·ͱΊ ൛ 📷🙆 🙆 2JJUB$POGFSFODF .BZ

ΞοϓσʔτΛॏͶΔߨԋͷ೥݄൛Ͱ͢ʢ࿈ࡌୈճ·Ͱऩ࿥ʣ IUUQTTQFBLFSEFDLDPNUXBEB ίϥϜ࿈ࡌͷୈճ·Ͱऩ࿥͍ͯ͠·͢

ߨԋͷจࣈى͜͠౳΋ࠓޙެ։༧ఆͰ͢ ެ։͞ΕͨΒTQFBLFSEFDLͷಉҰ63-Ͱ ࢿྉΛΞοϓσʔτ͠·͢

t-wada t_wada twada 📷🙆 📹🙅 🙆 ࣗݾ঺հ #QiitaConference

ٕज़ॻͷग़൛ʹؔΘ͍ͬͯ·͢

αόϯφศΓʜʜʁ

IUUQTUXBEBIBUFOBCMPHKQFOUSZXEQSFTTTBWBOOBDPMVNO 8%#13&44ʹίϥϜΛ࿈ࡌ͍ͯ͠·͢

IUUQTUXBEBIBUFOBCMPHKQFOUSZXEQSFTTTBWBOOBDPMVNO 8%#13&44ʹίϥϜΛ࿈ࡌ͍ͯ͠·͢

ΑΖ͓͘͠ئ͍͠·͢ 📷🙆 🙆 2JJUB$POGFSFODF

ֶश༻ςετ ِཅੑͱِӄੑ ςεταΠζ ςετμϒϧ ςετϐϥϛου ࣗಈςετͷαΠζμ΢ϯઓུ 🦁 "HFOEB࿈ࡌ֤ճͷςʔϚ

ֶͼΛࣗಈςετͱͯ͠ॻ͘ ଈ࣌ੑͱ࠶ݱੑ

ֶशྫ1)1ͷ%BUF5JNFͱ%BUF5JNF*NNVUBCMF IUUQTXXXQIQOFUNBOVBMKBDMBTTEBUFUJNFJNNVUBCMFQIQ

/** * @test * @group learning */ public function DateTimeのaddは自身の状態を変更しつつ自身を返す(): void { $halloween = new \DateTime('2021-10-31'); $oneYear = \DateInterval::createFromDateString('1 year'); $halloween2022 = $halloween->add($oneYear); $this->assertSame($halloween, $halloween2022); $this->assertEquals('2022-10-31', $halloween->format('Y-m-d')); $this->assertEquals('2022-10-31', $halloween2022->format('Y-m-d')); } /** * @test * @group learning */ public function DateTimeImmutableのaddは自身の状態を変更せず新しい状態を伴う新しいインスタンスを返す(): void { $halloween = new \DateTimeImmutable('2021-10-31'); $oneYear = \DateInterval::createFromDateString('1 year'); $halloween2022 = $halloween->add($oneYear); $this->assertNotSame($halloween, $halloween2022); $this->assertEquals('2021-10-31', $halloween->format('Y-m-d')); $this->assertEquals('2022-10-31', $halloween2022->format('Y-m-d')); } %BUF5JNFͱ%BUF5JNF*NNVUBCMFͷҧ͍Λֶशςετʹ͢Δ ֶशςετʢֶͼ͕໨తͷςετʣΛ ݟ෼͚ΔͨΊʹ MFBSOJOHλάΛ͚͍ͭͯ·͢ ֶ͕͜͜ͼ ֶ͕͜͜ͼ

ٙ໰Λςετʹ͢Δ

/** * @test * @group learning */ public function 同じ時刻を指している場合はタイムゾーンが異なっても等価とみなされる(): void { $utc = new DateTimeImmutable('2021-12-24T15:00:00', new DateTimeZone('UTC')); $jst = new DateTimeImmutable('2021-12-25T00:00:00', new DateTimeZone('Asia/Tokyo')); $this->assertTrue($utc == $jst); } ٙ໰Λςετʹ͢Δ ςετʹฉ͍ͯΈΕ͹͍͍

ڻ͖Λςετʹ͢Δ ྫ͑͹ʜʜ

ί ϯ ε τ ϥ Ϋ λ ͸ Ұ ճ ͠ ͔ ݺ ΂ ͳ ͍ ͱ ࡨ ֮ ͠ ͯ ͍ ͨ ʁ ㅟ ㅟ ㅟ ㅟ ㅟ ㅟ ㅟ ㅟ ㅟ ㅟ ㅟ ㅟ ㅟ ㅟ ㅟ Ұ ମ ͍ ͭ ͔ Β ŠŠŠŠŠŠ

/** * @test * @group learning */ public function コンストラクタをもう一度呼ぶと破壊的変更ができてしまう(): void { $dt = new \DateTimeImmutable('2021-12-24'); $this->assertSame('2021-12-24', $dt->format('Y-m-d')); $dt->__construct('2022-01-01'); $this->assertSame('2022-01-01', $dt->format('Y-m-d')); } ͳΜʜʜͩͱʜʜʂʁ ໌ࣔతʹݺ΂ͯ͠·͏ ༨ஊ͜ͷςετίʔυΛ͖͔͚ͬʹQIQTSDʹJTTVFͱͯ͠ใࠂ͞Εɺٞ࿦͕ߦΘΕ·ͨ͠ɻ IUUQTHJUIVCDPNQIQQIQTSDJTTVFT ༨ஊ͜ͷςετίʔυΛ͖͔͚ͬʹ੩తղੳπʔϧ1)14UBOͱ1TBMNʹػೳఏҊ͕ߦΘΕɺ 1)14UBOʹ!NVOP@͞Μ͕࡞੒ͨ͠QVMMSFRVFTU͕࠾༻͞ΕɺϦϦʔε͞Ε·ͨ͠ɻ IUUQTHJUIVCDPNQIQTUBOQIQTUBOTSDQVMM

ֶश༻ςετ ِཅੑͱِӄੑ ςεταΠζ ςετμϒϧ ςετϐϥϛου ࣗಈςετͷαΠζμ΢ϯઓུ "HFOEB࿈ࡌ֤ճͷςʔϚ 🦁

ࣗಈςετͷ৴པੑΛ Ή͠͹Ήݱ৅Λཧղ͢Δ

ςετࣗಈԽͱاۀͷۀ੷ͷҼՌؔ܎ IUUQTXXXBNB[PODPKQEQ ςετͷࣗಈԽʹ͓͍ͯɺ*5ύϑΥʔϚϯεͷ 
 ༧ଌई౓ͱͳΓ͏Δ͜ͱ͕൑໌ͨ͠ͷ͸࣍ͷͭ ৴པੑͷߴ͍ࣗಈςετΛඋ͑Δ͜ͱ ։ൃऀओମͰड͚ೖΕςετΛ࡞੒ɾ؅ཧ͠ɺ 
 खݩͷ։ൃ؀ڥͰ؆୯ʹ࠶ݱɾमਖ਼Ͱ͖Δ͜ͱ ʰ-FBOͱ%FW0QTͷՊֶʱQʢ˞༁ΛҰ෦มߋʣ

IUUQTXXXBNB[PODPKQEQ ςετʹ߹֨ͨ͠ιϑτ΢ΣΞͰ͋Ε͹ϦϦʔεՄೳɺෆ߹֨Ͱ͋Ε͹ॏେͳ ෆ۩߹͕͋ΔɺͱνʔϜ͕֬৴Ͱ͖ΔΑ͏ͳςετΛ࣮ࢪ͍ͯ͠Δ͜ͱ ޡݕ஌ʢِཅੑGBMTFQPTJUJWFʣ΍ݟಀ͠ʢِӄੑGBMTFOFHBUJWFʣ͕ଟ ͘ɺ৴པੑʹ͚ܽΔςετεΠʔτ͕͋·Γʹ΋ଟ͗͢Δ ৴པ౓ͷߴ͍ςετεΠʔτΛ࡞Γ্͛Δܧଓతͳ౒ྗͱ 
 ౤ࢿ͸Ձ஋͕͋Δ ʰ-FBOͱ%FW0QTͷՊֶʱQʢ˞༁ΛҰ෦มߋʣ ৴པੑͷߴ͍ࣗಈςετΛඋ͑Δ͜ͱ

ِཅੑͱِӄੑ IUUQTHJIZPKQEFWTFSJBMTBWBOOBMFUUFS

ِཅੑͱِӄੑͷύλʔϯ w ِཅੑ w ੬͍ςετ CSJUUMFUFTU GSBHJMFUFTU w ৴པෆೳςετ fl BLZUFTU w ِӄੑ w ۭৼΓ w ΧόϨοδෆ଍ w ςετର৅ϩδοΫͷςετίʔυ΁ͷ࿙Εग़͠

// プロダクトコード class Item { // コンストラクタ割愛 tax_amount() { const rate = (this.tax_rate / 100); return (this.price / (1 + rate)) * rate; } } // テストコード it('税込価格から税額を返す', () => { const item = new Item('技評茶', 130, 8); const expected = (130 / (1 + (8 / 100))) * (8 / 100); assert.equal(item.tax_amount(), expected); }); ྫςετର৅ϩδοΫͷςετίʔυ΁ͷ࿙Εग़͠ ԁະຬͷ୺਺͕ൃੜ͢Δ όά͕͋Δ ςετίʔυͷํ΋ಉ͡ϩδοΫͰ ظ଴஋Λܭࢉ͍ͯ͠ΔͷͰ ςετ͕੒ޭͯ͠͠·͏

৴པෆೳੑʢ fl BLJOFTTʣ͕ʹ઀ۙ͢Δͱɺςετ͸Ձ஋Λࣦ͍࢝ΊΔ IUUQTXXXPSFJMMZDPKQCPPLT ʰ(PPHMFͷιϑτ΢ΣΞΤϯδχΞϦϯάʱQ

ֶश༻ςετ ِཅੑͱِӄੑ ςεταΠζ ςετμϒϧ ςετϐϥϛου ࣗಈςετͷαΠζμ΢ϯઓུ "HFOEB࿈ࡌ֤ճͷςʔϚ 🦁

ࣗಈςετͱ$*ʹϑΟοτ͢Δ ໌֬ͳςετ෼ྨج४

օ͞Μʹ͓࢕͍͠·͢ 🙋🙋🙋 σʔλϕʔεʹΞΫηε͢Δͷ͸Ϣχοτςετ :FT/P ωοτϫʔΫʹΞΫηε͢Δͷ͸Ϣχοτςετ :FT/P ϑΝΠϧʹΞΫηε͢Δͷ͸Ϣχοτςετ :FT/P ݱࡏ࣌ࠁʹΞΫηε͢Δͷ͸Ϣχοτςετ :FT/P ґଘઌͷΫϥεʹຊ෺Λ࢖͏ͷ͸Ϣχοτςετ :FT/P

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4NBMM 
 ʢ୯Ұϓϩηεʣ .FEJVN 
 ʢ୯ҰϚγϯʣ -BSHF 
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4NBMM 
 ʢ୯Ұϓϩηεʣ .FEJVN 
 ʢ୯ҰϚγϯʣ -BSHF 
 ʢ੍໿ͳ͠ʣ 6OJU ൺ཰ େ͍ʹਪ঑ ආ͚͍͕ͨ ͔ͨ͠ͳ͍ͱ͖΋ ࠷ѱ͕ͩ Α͘ݟ͔͚Δ *OUFHSBUJPO ൺ཰ ॻ͚ΔͳΒ ίεύྑ͠ ී௨ Ͱ͖Ε͹ ආ͚͍ͨ && ൺ཰ ݪཧ্ෆՄೳʹ͍͕ۙ খ͍͞γεςϜͳΒՄೳʁ খ͍͞γεςϜ ͳΒՄೳ ී௨͔ͭ $6+ʹߜΓ͍ͨ 5FTU4DPQF 5FTU4J[F 5FTU4DPQFͱ5FTU4J[F ίεύྑ͠ ίεύѱ͠

ֶश༻ςετ ِཅੑͱِӄੑ ςεταΠζ ςετμϒϧ ςετϐϥϛου ࣗಈςετͷαΠζμ΢ϯઓུ "HFOEB࿈ࡌ֤ճͷςʔϚ 🦁

஧࣮ੑͱܾఆੑͷ τϨʔυΦϑΛཧղ͢Δ

IUUQYVOJUQBUUFSOTDPN5FTU%PVCMFIUNM ςετμϒϧࣗಈςετ༻ͷِ෺

IUUQYVOJUQBUUFSOTDPN5FTU%PVCMFIUNM ςετμϒϧͷ෼ྨʢY651ʣ

ςετμϒϧͷར఺ͱ஫ҙ఺ IUUQTXXXBNB[PODPKQEQ w ར఺ w ςετ͠ʹ͍͘΋ͷΛςετՄೳʹ͢Δ w ςετͷ଎౓ͱܾఆੑΛ޲্ͤ͞Δ w ஫ҙ఺ w ςετ͕੬͘ͳΓɺมߋΛ๦͛Δʢར఺ͷཪฦ͠ʣ w ςετͷِӄੑΛট͘ʢࣗ࡞ࣗԋςετʣ

ֶश༻ςετ ِཅੑͱِӄੑ ςεταΠζ ςετμϒϧ ςετϐϥϛου ࣗಈςετͷαΠζμ΢ϯઓུ "HFOEB࿈ࡌ֤ճͷςʔϚ 🦁

ࣗಈςετͷ৴པੑΛ த௕ظతʹอͭ ࠷దͳόϥϯε

Ϣχοτ ΠϯςάϨʔγϣϯ && ίετ ஧࣮ੑ ଎౓ ςετέʔε਺ ߴ ௿ ௿ ߴ ܾఆੑ ςετϐϥϛου

ςετϐϥϛουͱΞΠεΫϦʔϜίʔϯΞϯνύλʔϯ IUUQTXBUJSNFMPOCMPHJOUSPEVDJOHUIFTPGUXBSFUFTUJOHJDFDSFBNDPOF

ࠞཚ͸ʮϢχοτʯʮΠϯςάϨʔγϣϯʯͷղऍͷϒϨ͔Βੜ͕ͪ͡

Ϣχοτ ΠϯςάϨʔγϣϯ && ίετ ஧࣮ੑ ଎౓ ςετέʔε਺ ߴ ௿ ௿ ߴ ܾఆੑ ϒϨͷগͳ͍ςετͷ෼ྨج४͸ʜʜʁ

ίετ ஧࣮ੑ ଎౓ ߴ ௿ ௿ ߴ ܾఆੑ ϒϨͷগͳ͍ςετͷ෼ྨج४ˠςεταΠζ 4NBMM .FEJVN -BSHF ςετέʔε਺

IUUQTXBUJSNFMPOCMPHJOUSPEVDJOHUIFTPGUXBSFUFTUJOHJDFDSFBNDPOF 4NBMM .FEJVN -BSHF खಈςετ Ͱ΋ɺଟ͘ͷݱ৔Ͱ͸ΞΠεΫϦʔϜίʔϯ͔Β࢝·ΔʢͦΕ͸ѱ͍͜ͱͰ͸ͳ͍ʣ

ֶश༻ςετ ِཅੑͱِӄੑ ςεταΠζ ςετμϒϧ ςετϐϥϛου ࣗಈςετͷαΠζμ΢ϯઓུ "HFOEB࿈ࡌ֤ճͷςʔϚ 🦁

Ͳ͏΍ͬͯΞΠεΫϦʔϜίʔϯΛϐϥϛουʹ͢Δ͔ IUUQTXBUJSNFMPOCMPHJOUSPEVDJOHUIFTPGUXBSFUFTUJOHJDFDSFBNDPOF 4NBMM .FEJVN -BSHF खಈςετ 4NBMM .FEJVN -BSHF

IUUQTXBUJSNFMPOCMPHJOUSPEVDJOHUIFTPGUXBSFUFTUJOHJDFDSFBNDPOF 4NBMM .FEJVN -BSHF खಈςετ -BSHF͔Β.FEJVN΁

IUUQYVOJUQBUUFSOTDPN5FTU%PVCMFIUNM -BSHF͔Β.FEJVN΁'BLF0CKFDU 'BLF͸ࣗಈςετ༻ͷ୅ସ࣮૷ɻ %ZOBNP%#ʹର͢Δ%ZOBNP%#MPDBM΍MPDBLTUBDL͕୅දྫɻ ίϯςφͰಈ࡞ͤ͞ΒΕΕ͹ςεταΠζ͕.FEJVNʹऩ·Δɻ

IUUQTXBUJSNFMPOCMPHJOUSPEVDJOHUIFTPGUXBSFUFTUJOHJDFDSFBNDPOF 4NBMM .FEJVN -BSHF खಈςετ .FEJVN͔Β4NBMM΁

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ΞΠεΫϦʔϜίʔϯ͔Βϐϥϛου΁ IUUQTXBUJSNFMPOCMPHJOUSPEVDJOHUIFTPGUXBSFUFTUJOHJDFDSFBNDPOF 4NBMM .FEJVN -BSHF खಈςετ 4NBMM .FEJVN -BSHF

ֶश༻ςετ ِཅੑͱِӄੑ ςεταΠζ ςετμϒϧ ςετϐϥϛου ࣗಈςετͷαΠζμ΢ϯઓུ 🦁 🦁 🦁 🦁 🦁 ͜Ε·Ͱͷ஌ݟΛ·ͱΊΔͱ

4NBMM .FEJVN -BSHF ίετ ஧࣮ੑ ଎౓ ςετέʔε਺ ߴ ௿ ௿ ߴ ܾఆੑ ·ͱΊςετμϒϧͰαΠζμ΢ϯͯ͠ɺ֤αΠζΛϐϥϛουܕʹ഑ஔ͠ɺςετશମͷ৴པੑΛҡ࣋͢Δ ςετμϒϧ ςετμϒϧ ςετ༰қੑઃܭ υϝΠϯઃܭ

͓ΘΓʹ

ࣦ৬ͷةػྑॻ͗͢Δ IUUQTCPPLNZOBWJKQFDQSPEVDUTEFUBJMJE

ࣦ৬ͷةػ͍͔ʹ΋ࢲͷݴ͍ͦ͏ͳ͜ͱΛݴ͏"* IUUQTUXJUUFSDPNLBXBTJNBTUBUVT

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͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠ 📷🙆 🙆 2JJUB$POGFSFODF